SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549


                          -----------------------------


                                    FORM 11-K

                               [X] ANNUAL REPORT
                        Pursuant to Section 15(d) of the
               Securities Exchange Act of 1934 [No Fee Required]


                   For the fiscal year ended December 31, 2002
                                       or
             [ ] Transition Report Pursuant to Section 15(d) of the
               Securities Exchange Act of 1934 [No Fee Required]

         For the transition period from ____________ to ______________.

Commission file number (of issuer):  1-5667

     A. Full title of the plan and the address of the plan, if different from
that of the issuer named below:

                          Cabot Retirement Savings Plan


     B. Name of issuer of the securities held pursuant to the plan and the
address of its principal executive office:

                                Cabot Corporation
                          Two Seaport Lane, Suite 1300
                        Boston, Massachusetts 02210-2019








                              REQUIRED INFORMATION

     The following financial statements and schedules have been prepared in
accordance with the financial reporting requirements of the Employee Retirement
Income Security Act of 1974, as amended:

1.   Statement of Net Assets Available for Plan Benefits, as of December 31,
     2002 and 2001.

2.   Statement of Changes in Net Assets Available for Plan Benefits, for the
     year ended December 31, 2002.

3.   Notes to Financial Statements.

4.   Supplemental Schedule - Schedule of Assets (Held at Year-End).




                                   SIGNATURES

     The Plan. Pursuant to the requirements of the Securities Exchange Act of
1934, the trustees (or other persons who administer the employee benefit plan)
have duly caused this annual report to be signed on its behalf by the
undersigned hereunto duly authorized.

                                            Cabot Retirement Savings Plan
                                            --------------------------------
                                            (Name of Plan)


Date:  June 27, 2003                        /s/ John A. Shaw
                                            ------------------------------------
                                            John A. Shaw
                                            Executive Vice President and
                                            Chief Financial Officer




                                       2




CABOT RETIREMENT SAVINGS PLAN
FINANCIAL STATEMENTS
FOR THE YEARS ENDED DECEMBER 31, 2002 AND 2001






CABOT RETIREMENT SAVINGS PLAN
INDEX TO FINANCIAL STATEMENTS AND SUPPLEMENTAL SCHEDULE
--------------------------------------------------------------------------------


                                                                         PAGE(S)

Financial Statements:
   Report of Independent Auditors                                           2

   Statements of Net Assets Available for Plan Benefits
     as of December 31, 2002 and 2001                                     3-4

   Statement of Changes in Net Assets Available for Plan Benefits
     for the year ended December 31, 2002                                   5

   Notes to Financial Statements                                         6-12

Supplemental Schedule*:
   Schedule of Assets (Held at End of Year)                                13




*  Other supplemental schedules required by 29 CFR 2520.103-10 of the Department
   of Labor's Rules and Regulations for Reporting and Disclosure under ERISA
   have been omitted because they are not applicable.




                                       1



                         REPORT OF INDEPENDENT AUDITORS


To the Participants and Administrator
of the Cabot Retirement Savings Plan:

In our opinion, the accompanying statements of net assets available for plan
benefits and the related statement of changes in net assets available for plan
benefits present fairly, in all material respects, the net assets available for
plan benefits of the Cabot Retirement Savings Plan (the "Plan") at December 31,
2002 and 2001, and the changes in net assets available for plan benefits for the
year ended December 31, 2002 in conformity with accounting principles generally
accepted in the United States of America. These financial statements are the
responsibility of the Plan's management; our responsibility is to express an
opinion on these financial statements based on our audits. We conducted our
audits of these statements in accordance with auditing standards generally
accepted in the United States of America, which require that we plan and perform
the audit to obtain reasonable assurance about whether the financial statements
are free of material misstatement. An audit includes examining, on a test basis,
evidence supporting the amounts and disclosures in the financial statements,
assessing the accounting principles used and significant estimates made by
management, and evaluating the overall financial statement presentation. We
believe that our audits provide a reasonable basis for our opinion.

Our audits were conducted for the purpose of forming an opinion on the basic
financial statements taken as a whole. The supplemental schedule of the schedule
of assets (held at end of year) is presented for the purpose of additional
analysis and is not a required part of the basic financial statements but is
supplementary information required by the Department of Labor's Rules and
Regulations for Reporting and Disclosure under the Employee Retirement Income
Security Act of 1974. This supplemental schedule is the responsibility of the
Plan's management. The supplemental schedule has been subjected to the auditing
procedures applied in the audits of the basic financial statements and, in our
opinion, is fairly stated in all material respects in relation to the basic
financial statements taken as a whole.


                                          /s/ PricewaterhouseCoopers LLP

June 6, 2003



                                       2




CABOT RETIREMENT SAVINGS PLAN
STATEMENT OF NET ASSETS AVAILABLE FOR PLAN BENEFITS
DECEMBER 31, 2002
--------------------------------------------------------------------------------



                                                 ALLOCATED        UNALLOCATED       TOTAL
                                                                       
ASSETS
Investments, at fair value                     $259,841,734      $126,931,967    $386,773,701
Participant loans receivable                      2,408,886                 -       2,408,886
Employer contribution receivable                  1,281,276                 -       1,281,276
Employee contributions receivable                         -                 -               -
                                               ------------      ------------    ------------
     Total assets                              $263,531,896      $126,931,967    $390,463,863
                                               ============      ============    ============

LIABILITIES
Current portion of notes payable               $          -      $  2,944,048    $  2,944,048
Long-term portion of notes payable                        -        47,525,971      47,525,971
                                               ------------      ------------    ------------
     Total liabilities                                    -        50,470,019      50,470,019
                                               ------------      ------------    ------------
     Net assets available for plan benefits    $263,531,896      $ 76,461,948    $339,993,844
                                               ============      ============    ============




   The accompanying notes are an integral part of these financial statements.

                                        3





CABOT RETIREMENT SAVINGS PLAN
STATEMENT OF NET ASSETS AVAILABLE FOR PLAN BENEFITS
DECEMBER 31, 2001
--------------------------------------------------------------------------------






                                                 ALLOCATED        UNALLOCATED       TOTAL
                                                                       
ASSETS
Investments, at fair value                     $336,012,507      $186,484,059    $522,496,566
Participant loans receivable                      2,368,458                 -       2,368,458
Employer contribution receivable                    338,935                 -         338,935
Employee contributions receivable                     1,125                             1,125
                                               ------------      ------------    ------------
     Total assets                              $338,721,025      $186,484,059    $525,205,084
                                               ============      ============    ============

LIABILITIES
Current portion of notes payable               $          -      $  2,712,126    $  2,712,126
Long-term portion of notes payable                        -        50,470,018      50,470,018
                                               ------------      ------------    ------------
     Total liabilities                                    -        53,182,144      53,182,144
                                               ------------      ------------    ------------
     Net assets available for plan benefits    $338,721,025      $133,301,915    $472,022,940
                                               ============      ============    ============






   The accompanying notes are an integral part of these financial statements.

                                        4






CABOT RETIREMENT SAVINGS PLAN
STATEMENT OF CHANGES IN NET ASSETS AVAILABLE FOR PLAN BENEFITS
FOR THE YEAR ENDED DECEMBER 31, 2002
--------------------------------------------------------------------------------







                                                 ALLOCATED        UNALLOCATED       TOTAL
                                                                       
ADDITIONS
Interest and dividend income                   $  5,248,658      $  2,678,171    $   7,926,829
Net appreciation (depreciation) in fair
 value of investments                           (75,194,881)      (47,043,941)    (122,238,822)
Share allocation of Cabot Corporation
 common and preferred stock, at fair value       10,087,677                 -       10,087,677
Employer contributions                            3,186,645         1,939,408        5,126,053
Employee contributions                           10,595,471                 -       10,595,471
                                               ------------      ------------    -------------
     Total additions                            (46,076,430)      (42,426,362)     (88,502,792)
                                               ------------      ------------    -------------

DEDUCTIONS
Benefits paid to participants                   (29,112,699)                -      (29,112,699)
Interest expense                                          -        (4,325,928)      (4,325,928)
Share allocation of Cabot Corporation
 common and preferred stock, at fair value                -       (10,087,677)     (10,087,677)
                                               ------------      ------------    -------------
     Total deductions                           (29,112,699)      (14,413,605)     (43,526,304)
                                               ------------      ------------    -------------

Net increase                                    (75,189,129)      (56,839,967)    (132,029,096)

Net assets available for plan benefits:
  Beginning of year                             338,721,025       133,301,915      472,022,940
                                               ------------      ------------    -------------
  End of year                                  $263,531,896      $ 76,461,948    $ 339,993,844
                                               ============      ============    =============






   The accompanying notes are an integral part of these financial statements.

                                        5






CABOT RETIREMENT SAVINGS PLAN
NOTES TO FINANCIAL STATEMENTS
--------------------------------------------------------------------------------


1.   DESCRIPTION OF THE PLAN

     GENERAL
     Cabot Corporation (the Company) initially adopted the Cabot Corporation
     Employee Stock Ownership Plan (the ESOP) in 1988. As of December 31, 2000,
     the Cabot Retirement Incentive Savings Plan (the CRISP) and the Cabot
     Employee Savings Plan (the CESP) were merged with and into the ESOP. The
     combined amended and restated plan, a defined contribution plan, was
     renamed the Cabot Retirement Savings Plan (the Plan). The Plan is subject
     to the Employee Retirement Income Security Act of 1974 (ERISA).

     The following brief description of the Plan is provided for general
     information purpose only. A detailed description of the Plan is available
     for inspection at principal locations of the Company.

     ELIGIBILITY
     All U.S. employees of the Company and its participating subsidiaries
     (except certain temporary and leased employees) are eligible to participate
     beginning on the later of the first day of employment or the date the
     employee is included in an employee group which participates. Company
     contributions, employee contributions and all earnings thereon are recorded
     in accounts set up for all eligible participants and are reflected as
     allocated assets in the statement of net assets available for plan
     benefits.

     EMPLOYEE CONTRIBUTIONS
     The participant may make contributions by means of a salary reduction
     arrangement to his or her account. Participants may elect to contribute,
     through a payroll deduction, amounts ranging up to 15% of their U.S.
     eligible compensation on a before-tax basis, an after-tax basis, or a
     combination thereof, subject to certain limitations under the Internal
     Revenue Code (the Code).

     EMPLOYER CONTRIBUTIONS
     In addition to any discretionary contributions, the Company's contribution
     is primarily in the forms of (i) a matching contribution of shares in the
     Cabot common stock fund or the Cabot preferred stock fund (the basic
     employer match), and (ii) a Cabot preferred stock allocation. These
     contributions are calculated and recorded on the last business day of the
     calendar quarters.

     Subject to certain collective bargaining agreements, the basic employer
     match is equal to 75% of a participant's eligible before-tax and after-tax
     contributions on up to 7.5% of the participant's eligible compensation.

     The preferred stock allocation is comprised of a total quarterly allocation
     of 742.574 shares of preferred stock. The allocation to each participant is
     based on the value of Cabot preferred stock, the number of shares allocated
     as dividends and total eligible compensation. In instances where a
     participant allocation is less than 4% of eligible compensation, the
     Company is required to remit a contribution to provide for 4% minimum
     allocation. Subject to certain collective bargaining agreements,
     participant allocations greater than 8% of eligible compensation are used
     to fund the basic employer match. In the event that the total allocation
     amount also exceeds the basic employer match, the surplus is contributed to
     participants based on total eligible compensation. Subject to certain
     bargaining agreements, the allocation is made to each participant's account
     who is employed on that date or has retired, died or becomes totally and
     permanently disabled during the quarter. Preferred stock which has not been
     allocated to participants but held by the plan is reflected as unallocated
     assets in the statement of net assets available for plan benefits.


                                       6


CABOT RETIREMENT SAVINGS PLAN
NOTES TO FINANCIAL STATEMENTS
--------------------------------------------------------------------------------


     In March 2001, the number of shares of preferred stock, including preferred
     stock dividends, which are released for allocation to participants'
     accounts changed to 742.574 shares from 750 shares. Also in March 2001, the
     Plan received a cash contribution from the Company totaling $1.7 million.
     The cash contribution was used to purchase Cabot common stock and was
     recorded as a Company contribution to the Plan's unallocated investment
     fund. The change in the number of shares released from allocation and the
     cash contribution from the Company adjusted the value of the unallocated
     assets held by the Plan to adequately secure the Plan's notes payable.

     FUNDING POLICY
     The total addition to each participant's account shall not exceed the
     lesser of either 100% of the participant's U.S. compensation (as defined by
     the Code) or $40,000.

     INVESTMENTS
     The employee's contribution will be allocated, at the employee's election,
     to one or more of ten funds established for investment of Plan assets:
     Vanguard Index Trust - 500 Portfolio (Vanguard 500 Portfolio), a growth and
     income fund, invests in all of the stocks included in the Standard & Poor's
     (S&P) 500 index in approximately the same proportions as they are
     represented in the S&P 500 index; Vanguard Windsor II, also a growth and
     income fund, is comprised of common stocks that the investment manager
     believes are undervalued in the marketplace; Vanguard Wellington Fund, a
     balanced fund, invests in bonds and stocks that, in the opinion of the
     investment manager, provide relative stability of income and principal and
     potential growth of capital and income, respectively; Vanguard Fixed Income
     Securities Fund Short-Term Federal Portfolio (Vanguard Short-Term Federal
     Portfolio), an income fund, that invests primarily in short-term U.S.
     Government and agency securities with maturities from one to three years;
     Vanguard Money Market Reserves-Federal Portfolio (Vanguard Federal
     Portfolio) invests solely in securities with maturities of one year or less
     issued by the U.S. Treasury and agencies of the U.S. Government; Vanguard
     Explorer Fund invests primarily in common stocks of small companies that,
     in the opinion of the investment manager, provide favorable prospects for
     above-average growth in market value; Vanguard PRIMECAP Fund seeks
     long-term growth of capital by investing principally in a portfolio of
     common stocks; Vanguard International Growth Portfolio seeks to provide
     long-term growth of capital and diversification overseas by investing in
     the stock of companies located outside the United States; Vanguard Total
     Bond Market Index Fund seeks a high level of interest income by investing
     in a large sampling that matches key characteristics of the Lehman Brother
     Aggregate Bond Index, which is a widely recognized measure of the entire
     taxable U.S. bond market; and the Cabot Common Stock Fund, which invests
     primarily in Cabot common stock.

     The preferred stock allocations are recorded in the Cabot Preferred Stock
     Fund, which invests primarily in Cabot preferred stock.

     In addition, Plan participants have retained a stock dividend received
     during 2000, and the earnings thereon, in the Cabot Microelectronics Common
     Stock Fund, which invests primarily in Cabot Microelectronics common stock.
     The Plan does not allow participants to contribute to the Cabot
     Microelectronics Common Stock Fund.



                                       7


CABOT RETIREMENT SAVINGS PLAN
NOTES TO FINANCIAL STATEMENTS
--------------------------------------------------------------------------------


     VESTING
     Each participant will at all times be 100% vested in his or her
     contributions. Effective January 1, 2002, all salaried participants will be
     vested in all company contributions and earnings thereon according to a
     five-year vesting schedule, which is 20% upon completion of two years of
     service, 40% upon completion of three years of service, 60% upon completion
     of four years of service, and 100% upon completion of five years of
     service. A participant's entire account balance becomes 100% vested and
     payable, upon the participant's attainment of age 65, upon the
     participant's early retirement (defined as age 55 with 10 years of service
     to the company), disability or death. Union members of the Plan are subject
     to their negotiated vesting schedules.

     BENEFITS
     The Plan requires, subject to certain collective bargaining agreements, all
     participant benefits to be paid in the form of a lump sum distribution.

     A participant may also withdraw up to 100% of before-tax contributions,
     upon showing a financial hardship exists but only after the participant has
     withdrawn all other vested benefits from the Plan and the maximum loan has
     been made from the participant's account. Participants with after-tax
     contributions may elect to withdraw these amounts at any time.

     If a participant leaves the Company for any other reason before retirement
     and his or her account balance is $5,000 or less, he or she will receive in
     a lump sum distribution of the vested portion of his or her account
     balance.

     A participant may elect to defer payment of a benefit until April 1
     following the year that the participant reaches age 70 1/2.

     LOANS
     Participants may obtain loans from the Plan in an amount not to exceed, in
     the aggregate, the lesser of $50,000 or 50% of the total vested amounts in
     the participant's account. Each loan must be paid in full within five years
     through payroll deductions and is secured by the participant's remaining
     account balance. Interest is charged at reasonable rates as determined by
     the Benefits Committee of Cabot Corporation. Interest rates on outstanding
     loans as of December 31, 2002 ranged from 6.75% to 10.91%.


2.   SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES

     BASIS OF PRESENTATION
     The financial statements of the Plan are prepared using the accrual method
     of accounting.

     USE OF ESTIMATES
     The preparation of financial statements in conformity with generally
     accepted accounting principles requires management to make estimates and
     assumptions that affect the reported amounts of assets and liabilities and
     disclosure of contingent assets and liabilities at the date of the
     financial statements and the reported amounts of additions and deductions
     during the reporting period. Actual results could differ from those
     estimates.


                                       8


CABOT RETIREMENT SAVINGS PLAN
NOTES TO FINANCIAL STATEMENTS
--------------------------------------------------------------------------------


     RISK AND UNCERTAINTIES
     The Plan allows for various investment options (as selected by the Plan
     administrator) in any combination of stocks, bonds, fixed income
     securities, mutual funds and other investment securities. Investment
     securities are exposed to various risks, such as interest rate, market and
     credit risks. Due to the level of risk associated with certain investment
     securities, it is at least reasonably possible that changes in the values
     of investment securities will occur in the near term and that such changes
     could materially affect participants' account balances and the amounts
     reported in the statements of net assets available for plan benefits.

     INVESTMENT VALUATION
     The preferred stock is valued by Duff and Phelps Capital Markets Co., an
     independent appraiser. The value of the preferred stock depends primarily
     on the Company's common stock value.

     Investments in common stock traded on a national securities exchange are
     valued at the last reported sale price on the last business day of the
     year. Investments in commingled funds and mutual funds are valued at the
     net asset value as of the end of the year. The short-term investment funds
     are carried at cost which approximates market value. Participant loans are
     valued at cost which approximates fair value.

     INVESTMENT TRANSACTIONS
     Purchases and sales of securities are reflected on a trade date basis. Gain
     or loss on sales of securities is based on average cost.

     Dividend income is reported on the ex-dividend date. Interest income is
     recorded as earned on the accrual basis.

     The Plan presents in the statement of changes in net assets the net
     realized and unrealized appreciation (depreciation) in the fair value of
     its investments which consists of realized gains or losses and unrealized
     appreciation or (depreciation) on those investments.

     BENEFIT PAYMENTS
     Benefits are recorded when paid.


3.   INVESTMENTS

     The fair value of investments held by the Plan by general type are as
     follows:



                                             DECEMBER 31,
                                   2002                          2001
                          ALLOCATED     UNALLOCATED    ALLOCATED     UNALLOCATED
                                                       

     Common stocks      $ 52,086,367   $          -   $ 80,886,558  $          -
     Preferred stocks     90,392,994    126,931,967    120,802,530   186,484,059
     Mutual funds        117,362,373              -    134,323,419             -
                        ------------   ------------   ------------  ------------
                        $259,841,734   $126,931,967   $336,012,507  $186,484,059
                        ============   ============   ============  ============



                                       9

CABOT RETIREMENT SAVINGS PLAN
NOTES TO FINANCIAL STATEMENTS
--------------------------------------------------------------------------------


     The fair value of investments held by the Plan that exceed 5% or more of
     net assets available for plan benefits as of December 31, 2002 and 2001 are
     as follows:



                                                       DECEMBER 31,
                                            2002                         2001
                                  ALLOCATED     UNALLOCATED     ALLOCATED      UNALLOCATED

                                                                 
     Vanguard Windsor II Fund     $15,463,200   $          -   $ 18,652,521   $          -
     Vanguard Federal Money
      Market Fund                  16,461,950              -     18,905,020              -
     Vanguard Wellington Fund      20,571,579              -     22,644,063              -
     Cabot common stock fund       39,148,257              -     55,975,292              -
     Cabot microelectronics
      common stock fund            12,938,109              -     24,911,267              -
     Cabot preferred stock fund    90,392,994    126,931,967    120,802,530    186,484,059
     Vanguard 500 portfolio fund   29,539,841              -     37,616,280              -




     The net appreciation (depreciation) in fair value of investments for the
     years ended December 31, 2002 and 2001 was as follows:



                                              2002            2001
                                                    
     Cabot preferred stock                $ (77,738,106)    $59,472,081
     Cabot common stock                     (23,016,503)      8,852,941
     Mutual fund                            (21,484,213)     (6,327,046)
                                          -------------     -----------
        Total                             $(122,238,822)    $61,997,976
                                          =============     ===========




     Each share of the preferred stock is convertible into shares of the
     Company's common stock, subject to certain events and anti-dilution
     adjustment provisions, and carries voting rights on an "as converted"
     basis. The conversion rate for one share of preferred stock to common stock
     was 146.3782 as of December 31, 2002 and 2001.

     On or after November 19, 1991, the Company has the right to cause the
     trustee to redeem preferred shares. Such shares shall be redeemed at their
     redemption price, and may be redeemed by the Company for cash, shares of
     the Company's common stock, or a combination thereof at the Company's
     option. As of December 31, 2002, the redemption price is $1,000 per share.
     In addition to the redemption price, any accrued and unpaid dividends will
     become payable on the redemption date.

     The issued shares of preferred stock are entitled to receive preferential
     and cumulative quarterly dividends and rank as to dividends and liquidation
     prior to the Company's Series A Junior Participating Preferred Stock and
     common stock.



                                       10


CABOT RETIREMENT SAVINGS PLAN
NOTES TO FINANCIAL STATEMENTS
--------------------------------------------------------------------------------

4.   NOTES PAYABLE

     Long-term debt consisted of the following:



                                                  DECEMBER 31,
                                             2002                 2001
                                                       
     Note due 2013, 8.29%                $50,470,019          $53,182,144




     In November 1988, the Plan borrowed $75,000,000 from an institutional
     lender in order to finance its purchase of 75,000 shares of the Company's
     Series B ESOP Convertible Preferred Stock. This debt accrues interest at a
     rate of 8.29% per annum, and is to be repaid in equal quarterly
     installments with final payment due on December 31, 2013. This debt is
     guaranteed by the assets in the unallocated fund and the Company.

     The aggregate principal amounts of long-term debt due for the next five
     fiscal years and thereafter are as follows:



     YEAR ENDED DECEMBER 31,

                                        
     2003                                  $ 2,944,048
     2004                                    3,195,802
     2005                                    3,469,084
     2006                                    3,765,736
     2007                                    4,087,755
     Thereafter                             33,007,594




5.   DEBT SERVICE CONTRIBUTIONS

     The Company contributes to the Plan on a quarterly basis the difference
     between dividends earned on the leveraged preferred stock and the payment
     due by the Plan to the lender.


6.   FORFEITURES

     Upon termination of a participant from the Plan before being fully vested,
     the nonvested portion of the Company contributions is forfeited. The Plan
     allows the Company to offset company contributions with participant
     forfeitures. During 2002, the Company utilized $708,201, which represented
     all available forfeitures to offset the Company match and service the
     Plan's debt. As of December 31, 2002, participant forfeitures totaled
     $9,853 and are recorded in the statement of net assets available for plan
     benefits.


7.   ADMINISTRATIVE EXPENSES

     All administrative expenses associated with the operation of the Plan were
     paid by the Company during the year ended December 31, 2002. However, under
     the terms of the Plan, such costs may be charged to the Plan.



                                       11


CABOT RETIREMENT SAVINGS PLAN
NOTES TO FINANCIAL STATEMENTS
--------------------------------------------------------------------------------


8.   TAX STATUS

     In a letter dated May 14, 2002, the Internal Revenue Service advised the
     Company of its favorable determination with respect to the qualified status
     of the Plan, as amended and restated, under the Code. The Plan is intended
     to qualify as a profit sharing plan under section 401(a) of the Code that
     contains a stock bonus feature constituting an employee stock ownership
     plan under section 4975(e) of the Code. The plan administrator and counsel
     believe that the Plan is designed and is currently being operated in
     compliance with the applicable requirements of the IRC. Therefore, no
     provision for income tax has been accrued.


9.   PLAN TERMINATION

     The Plan was established with the intention that it will continue
     indefinitely. However, the Company reserves the right to suspend its
     contributions or to terminate the Plan at any time. In the event the Plan
     is terminated, all participants become 100% vested and the assets of the
     Plan, after payment of any expenses, taxes or proper charges of the
     trustee, will be allocated in accordance with the provisions of ERISA.


10.  PARTY-IN-INTEREST

     The short-term investment fund consists of units of common and collective
     trusts managed by State Street Bank. The Plan's investment options also
     include certain mutual funds of The Vanguard Group. State Street Bank and
     Vanguard Fiduciary Trust Company are the trustees of the Plan's assets and,
     therefore, these transactions qualify as party-in-interest. In addition,
     the Plan invests in common and preferred stock of the plan sponsor and
     these transactions qualify as party-in-interest. Finally, the Plan provides
     loans to certain participants which also qualify as party-in-interest
     transactions.



                                       12


CABOT RETIREMENT SAVINGS PLAN
SCHEDULE OF ASSETS (HELD AT END OF YEAR)
DECEMBER 31, 2002
--------------------------------------------------------------------------------



                                                                         CURRENT
DESCRIPTION OF INVESTMENT                                COST             VALUE

                                                                
Preferred stock of Cabot Corporation*                $ 74,969,258     $ 217,324,961
Common stock of Cabot Corporation*                     28,279,763        39,148,257
Common stock of Cabot Microelectronic Corporation      13,123,793        12,938,109
Vanguard 500 Portfolio Fund*                           39,910,281        29,539,841
Vanguard Explorer Fund*                                 8,598,656         6,963,784
Vanguard Federal Portfolio Fund*                       16,461,950        16,461,950
Vanguard International Growth Portfolio Fund*           3,004,569         2,271,740
Vanguard PRIMECAP Fund*                                17,617,734        12,969,770
Vanguard Short-term Federal Portfolio*                  9,276,647         9,497,092
Vanguard Total Bond Market Index Fund*                  3,561,008         3,623,418
Vanguard Wellington Fund*                              23,530,602        20,571,579
Vanguard Windsor II Fund*                              19,566,707        15,463,200
Participant Loans - stated interest rates ranging
 from 6.75% - 10.91%*                                   2,408,886         2,408,886
                                                     ------------      ------------
Total investments                                    $260,309,854      $389,182,587
                                                     ============      ============



*Party-in-interest



                                       13


                                  Exhibit Index

Exhibit Number
--------------

Exhibit 23 -- Consent of Independent Accountants.

Exhibit 99.1 -- Certification Pursuant to Section 906 of the Sarbanes-Oxley Act
                of 2002.