Exhibit 99.8

Director Form of Restricted Stock Agreement

RESTRICTED STOCK AGREEMENT

IMMUNOGEN, INC.

AGREEMENT made as of the day of , 200 (the “Grant Date”), between ImmunoGen, Inc. (the “Company”), a Massachusetts corporation, and (the “Non-Employee Director”).

WHEREAS, the Company has adopted the ImmunoGen, Inc. 2006 Employee, Director and Consultant Equity Incentive Plan (the “Plan”) to promote the interests of the Company by providing an incentive for employees, directors and consultants of the Company or its Affiliates;

WHEREAS, pursuant to the provisions of the Plan, the Company desires to offer to the Non-Employee Director shares of the Company’s common stock, $.01 par value per share (“Common Stock”), in accordance with the provisions of the Plan, all on the terms and conditions hereinafter set forth;

WHEREAS, Non-Employee Director wishes to accept said offer; and

WHEREAS, the parties hereto understand and agree that any terms used and not defined herein have the meanings ascribed to such terms in the Plan.

NOW, THEREFORE, in consideration of the promises and the mutual covenants contained herein and for other good and valuable consideration, the receipt and sufficiency of which are hereby acknowledged, the parties hereto hereby agree as follows:

1. Terms of Grant. The Non-Employee Director hereby accepts the offer of the Company to issue to the Non-Employee Director, in accordance with the terms of the Plan and this Agreement, ( ) Shares of the Company’s Common Stock (such shares, subject to adjustment pursuant to Section 24 of the Plan and Subsection 2.1(h) hereof, the “Granted Shares”) at a purchase price per share of $.01 (the “Purchase Price”), receipt of which is hereby acknowledged by the Non-Employee Director’s prior service to the Company and which amount will be reported as income on the Non-Employee Director’s 1099 for this calendar year(1).

2.1. Forfeiture Provisions.

(a) Lapsing Forfeiture Right. In the event that for any reason the Non-Employee Director is no longer a director of the Company (such event being the “Termination”) prior to , the Non-Employee Director (or the Non-Employee Director’s Survivor) shall, on the date of Termination, immediately forfeit to the Company (or its designee) all of the Granted Shares which have not yet lapsed in accordance with the schedule set forth below (the “Lapsing Forfeiture Right”).

The Company’s Lapsing Forfeiture Right is as follows:

(1) Consider statutory minimum purchase price per share, if applicable (e.g., Delaware requires at least par value).

(i) If the Non-Employee Director’s Termination is prior to [the first anniversary of the Grant Date], all of the Granted Shares shall be forfeited to the Company.

(ii) If the Non-Employee Director’s Termination is on or after [the first anniversary of the Grant Date] but prior to , % of the Granted Shares shall be forfeited to the Company.

(b) Effect of Termination for Disability or upon Death. The following rules apply if the Non-Employee Director’s Termination is by reason of Disability or death: to the extent the Company’s Lapsing Forfeiture Right has not lapsed as of the date of Disability or death, as case may be, the Non-Employee Director shall forfeit to the Company any or all of the Granted Shares subject to such Lapsing Forfeiture Right; provided, however, that the Company’s Lapsing Forfeiture Right shall be deemed to have lapsed to the extent of a pro rata portion of the Granted Shares through the date of Disability or death, as would have lapsed had the Non-Employee Director not become Disabled or died, as the case may be. The proration shall be based upon the number of days accrued in such current vesting period prior to the Non-Employee Director’s date of Disability or death, as the case may be.

(c) Effect of a For Cause Termination. Notwithstanding anything to the contrary contained in this Agreement, in the event the Company terminates the Non-Employee Director’s service for Cause (as defined in the Plan) or in the event the Administrator determines, within one year after the Non-Employee Director’s termination, that either prior or subsequent to the Non-Employee Director’s termination the Non-Employee Director engaged in conduct that would constitute Cause, all of the Granted Shares then held by the Non-Employee Director shall be forfeited to the Company immediately as of the time the Non-Employee Director is notified that he or she has been terminated for Cause or that he or she engaged in conduct which would constitute Cause.

(d) Effect of Change of Control. Except as otherwise provided in Subsection 2.1(c) above, the Company’s Lapsing Forfeiture Right shall terminate, and the Non-Employee Director’s ownership of all Granted Shares then owned by the Non-Employee Director shall become vested upon a Change of Control (as defined in the Plan).

(e) Escrow. The certificates representing all Granted Shares acquired by the Non-Employee Director hereunder which from time to time are subject to the Lapsing Forfeiture Right shall be delivered to the Company and the Company shall hold such Granted Shares in escrow as provided in this Subsection 2.1(e). The Company shall promptly release from escrow and deliver to the Non-Employee Director the whole number of Granted Shares, if any, as to which the Company’s Lapsing Forfeiture Right has lapsed and without the legend set forth in Section 5. In the event of forfeiture to the Company of Granted Shares subject to the Lapsing Forfeiture Right, the Company shall release from escrow and cancel a certificate for the number of Granted Shares so forfeited. Any securities distributed in respect of the Granted Shares held in escrow, including, without limitation, shares issued as a result of stock splits, stock dividends or other recapitalizations, shall also be held in escrow in the same manner as the Granted Shares.

(f) Prohibition on Transfer. The Non-Employee Director recognizes and agrees that all Granted Shares which are subject to the Lapsing Forfeiture Right may not be sold, transferred, assigned, hypothecated, pledged, encumbered or otherwise disposed of, whether voluntarily or by operation of law, other than to the Company (or its designee). However, the Non-Employee Director, with the approval of the Administrator, may transfer the Granted Shares for no consideration to or for the benefit of the Non-Employee Director’s Immediate Family (including, without limitation, to a trust for the benefit of the Non-Employee Director’s Immediate Family or to a partnership or limited liability company for one or

more members of the Non-Employee Director’s Immediate Family), subject to such limits as the Administrator may establish, and the transferee shall remain subject to all the terms and conditions applicable to this Agreement prior to such transfer and each such transferee shall so acknowledge in writing as a condition precedent to the effectiveness of such transfer. The term “Immediate Family” shall mean the Non-Employee Director’s spouse, former spouse, parents, children, stepchildren, adoptive relationships, sisters, brothers, nieces and nephews and grandchildren (and, for this purpose, shall also include the Non-Employee Director.) The Company shall not be required to transfer any Granted Shares on its books which shall have been sold, assigned or otherwise transferred in violation of this Subsection 2.1(f), or to treat as the owner of such Granted Shares, or to accord the right to vote as such owner or to pay dividends to, any person or organization to which any such Granted Shares shall have been so sold, assigned or otherwise transferred, in violation of this Subsection 2.1(f).

(g) Failure to Deliver Granted Shares to be Forfeited. In the event that the Granted Shares to be forfeited to the Company under this Agreement are not in the Company’s possession pursuant to Subsection 2.1(e) above or otherwise and the Non-Employee Director or the Non-Employee Director’s Survivor fails to deliver such Granted Shares to the Company (or its designee), the Company may immediately take such action as is appropriate to transfer record title of such Granted Shares from the Non-Employee Director to the Company (or its designee) and treat the Non-Employee Director and such Granted Shares in all respects as if delivery of such Granted Shares had been made as required by this Agreement. The Non-Employee Director hereby irrevocably grants the Company a power of attorney which shall be coupled with an interest for the purpose of effectuating the preceding sentence.

(h) Adjustments. The Plan contains provisions covering the treatment of Shares in a number of contingencies such as stock splits and mergers. Provisions in the Plan for adjustment with respect to the Granted Shares and the related provisions with respect to successors to the business of the Company are hereby made applicable hereunder and are incorporated herein by reference.

2.2 General Restrictions on Transfer of Granted Shares.

(a) The Non-Employee Director agrees that in the event the Company proposes to offer for sale to the public any of its equity securities and such Non-Employee Director is requested by the Company and any underwriter engaged by the Company in connection with such offering to sign an agreement restricting the sale or other transfer of Shares, then it will promptly sign such agreement and will not transfer, whether in privately negotiated transactions or to the public in open market transactions or otherwise, any Shares or other securities of the Company held by him or her during such period as is determined by the Company and the underwriters, not to exceed 90 days following the closing of the offering, plus such additional period of time as may be required to comply with Marketplace Rule 2711 of the National Association of Securities Dealers, Inc. or similar rules thereto (such period, the “Lock-Up Period”). Such agreement shall be in writing and in form and substance reasonably satisfactory to the Company and such underwriter and pursuant to customary and prevailing terms and conditions. Notwithstanding whether the Non-Employee Director has signed such an agreement, the Company may impose stop-transfer instructions with respect to the Shares or other securities of the Company subject to the foregoing restrictions until the end of the Lock-Up Period.

(b) The Non-Employee Director acknowledges and agrees that neither the Company nor, its shareholders nor its directors and officers, has any duty or obligation to disclose to the Non-Employee Director any material information regarding the business of the Company or affecting the value of the Shares before, at the time of, or following a Termination, including, without limitation, any information concerning plans for the Company to make a public offering of its securities or to be acquired by or merged with or into another firm or entity.

3. Securities Law Compliance. The Non-Employee Director specifically acknowledges and agrees that any sales of Granted Shares shall be made in accordance with the requirements of the Securities Act of 1933, as amended.

4. Rights as a Stockholder. The Non-Employee Director shall have all the rights of a stockholder with respect to the Granted Shares, including voting and dividend rights, subject to the transfer and other restrictions set forth herein and in the Plan.

5. Legend. In addition to any legend required pursuant to the Plan, all certificates representing the Granted Shares to be issued to the Non-Employee Director pursuant to this Agreement shall have endorsed thereon a legend substantially as follows:

“The shares represented by this certificate are subject to restrictions set forth in a Restricted Stock Agreement dated as of with this Company, a copy of which Agreement is available for inspection at the offices of the Company or will be made available upon request.”

6. Incorporation of the Plan. The Non-Employee Director specifically understands and agrees that the Granted Shares issued under the Plan are being sold to the Non-Employee Director pursuant to the Plan, a copy of which Plan the Non-Employee Director acknowledges he or she has read and understands and by which Plan he or she agrees to be bound. The provisions of the Plan are incorporated herein by reference.

7. Tax Liability of the Non-Employee Director and Payment of Taxes. The Non-Employee Director acknowledges and agrees that any income or other taxes due from the Non-Employee Director with respect to the Granted Shares issued pursuant to this Agreement, including, without limitation, the Lapsing Forfeiture Right, shall be the Non-Employee Director’s responsibility. Without limiting the foregoing, the Non-Employee Director agrees that, to the extent that the lapsing of restrictions on disposition of any of the Granted Shares or the declaration of dividends on any such shares before the lapse of such restrictions on disposition results in the Non-Employee Director’s being deemed to be in receipt of earned income under the provisions of the Code, the Company shall be entitled to immediate payment from the Non-Employee Director of the amount of any tax required to be withheld by the Company.

Upon execution of this Agreement, the Non-Employee Director may file an election under Section 83 of the Code in substantially the form attached as Exhibit B. The Non-Employee Director acknowledges that if he does not file such an election, as the Granted Shares are released from the Lapsing Forfeiture Right in accordance with Section 2.1, the Non-Employee Director will have income for tax purposes equal to the fair market value of the Granted Shares at such date, less the price paid for the Granted Shares by the Non-Employee Director.(2)

(2) If the Shares are purchased at fair market value then the 83(b) election would be protective in nature and would not result in any additional tax on purchase of the Shares. If the Shares are being purchased at a discount from fair market value, the 83(b) election accelerates the timing of the taxation to the time of the grant, and later dispositions are taxed at capital gain rates. If the 83(b) election is not made then the tax is paid at the time the restrictions lapse (which could result in a higher possible taxable spread at that time). An 83(b) election must be made within 30 days of the grant.

If the Company pays cash dividends and an 83(b) election is filed, dividends receive dividend tax treatment. However, if no 83(b) election is made (as is the case with most public companies) the Employee will pay ordinary income tax rates on the cash dividend payments until the restrictions on the shares underlying those dividends lapse.

If no 83(b) election is filed consider adding the following to the Agreement: The Non-Employee Director has agreed not to file an election with respect to the Granted Shares under Section 83 of the Code and has obtained the advice or has been given the opportunity to obtain the advice of his or her tax advisors with respect to the tax consequences of the purchase of the Granted Shares and the provisions of this Agreement.

8. Equitable Relief. The Non-Employee Director specifically acknowledges and agrees that in the event of a breach or threatened breach of the provisions of this Agreement or the Plan, including the attempted transfer of the Granted Shares by the Non-Employee Director in violation of this Agreement, monetary damages may not be adequate to compensate the Company, and, therefore, in the event of such a breach or threatened breach, in addition to any right to damages, the Company shall be entitled to equitable relief in any court having competent jurisdiction. Nothing herein shall be construed as prohibiting the Company from pursuing any other remedies available to it for any such breach or threatened breach.

9. No Obligation to Maintain Relationship. The Company is not by the Plan or this Agreement obligated to continue the Non-Employee Director as a director of the Company. The Non-Employee Director acknowledges: (i) that the Plan is discretionary in nature and may be suspended or terminated by the Company at any time; (ii) that the grant of the Shares is a one-time benefit which does not create any contractual or other right to receive future grants of shares, or benefits in lieu of shares; (iii) that the Non-Employee Director’s participation in the Plan is voluntary; and (iv) that the Shares are not part of normal or expected compensation for purposes of calculating any severance, resignation, redundancy, end of service payments, bonuses, long-service awards, pension or retirement benefits or similar payments.

10. Notices. Any notices required or permitted by the terms of this Agreement or the Plan shall be given by recognized courier service, facsimile, registered or certified mail, return receipt requested, addressed as follows:

If to the Company:

ImmunoGen, Inc.

Attn: Finance

128 Sidney Street

Cambridge, MA 02139

If to the Non-Employee Director:

EMPLOYEE NAME AND ADDRESS

or to such other address or addresses of which notice in the same manner has previously been given. Any such notice shall be deemed to have been given on the earliest of receipt, one business day following delivery by the sender to a recognized courier service, or three business days following mailing by registered or certified mail.

11. Benefit of Agreement. Subject to the provisions of the Plan and the other provisions hereof, this Agreement shall be for the benefit of and shall be binding upon the heirs, executors, administrators, successors and assigns of the parties hereto.

12. Governing Law. This Agreement shall be construed and enforced in accordance with the laws of the Commonwealth of Massachusetts, without giving effect to the conflict of law principles thereof.

13. Severability. If any provision of this Agreement is held to be invalid or unenforceable by a court of competent jurisdiction, then such provision or provisions shall be modified to the extent necessary to make such provision valid and enforceable, and to the extent that this is impossible, then such provision shall be deemed to be excised from this Agreement, and the validity, legality and enforceability of the rest of this Agreement shall not be affected thereby.

14. Entire Agreement. This Agreement, together with the Plan, constitutes the entire agreement and understanding between the parties hereto with respect to the subject matter hereof and supersedes all prior oral or written agreements and understandings relating to the subject matter hereof. No statement, representation, warranty, covenant or agreement not expressly set forth in this Agreement shall affect or be used to interpret, change or restrict the express terms and provisions of this Agreement provided, however, in any event, this Agreement shall be subject to and governed by the Plan.

15. Modifications and Amendments; Waivers and Consents. The terms and provisions of this Agreement may be modified or amended as provided in the Plan. Except as provided in the Plan, the terms and provisions of this Agreement may be waived, or consent for the departure therefrom granted, only by written document executed by the party entitled to the benefits of such terms or provisions. No such waiver or consent shall be deemed to be or shall constitute a waiver or consent with respect to any other terms or provisions of this Agreement, whether or not similar. Each such waiver or consent shall be effective only in the specific instance and for the purpose for which it was given, and shall not constitute a continuing waiver or consent.

16. Consent of Spouse/Domestic Partner. If the Non-Employee Director has a spouse or domestic partner as of the date of this Agreement, the Non-Employee Director’s spouse or domestic partner shall execute a Consent of Spouse/Domestic Partner in the form of Exhibit A hereto, effective as of the date hereof. Such consent shall not be deemed to confer or convey to the spouse or domestic partner any rights in the Granted Shares that do not otherwise exist by operation of law or the agreement of the parties. If the Non-Employee Director subsequent to the date hereof, marries, remarries or applies to the Company for domestic partner benefits, the Non-Employee Director shall, not later than 60 days thereafter, obtain his or her new spouse/domestic partner’s acknowledgement of and consent to the existence and binding effect of all restrictions contained in this Agreement by having such spouse/domestic partner execute and deliver a Consent of Spouse/Domestic Partner in the form of Exhibit A.

17. Counterparts. This Agreement may be executed in one or more counterparts, and by different parties hereto on separate counterparts, each of which shall be deemed an original, but all of which together shall constitute one and the same instrument.

18. Data Privacy. By entering into this Agreement, the Non-Employee Director: (i) authorizes the Company and each Affiliate, and any agent of the Company or any Affiliate administering the Plan or providing Plan record keeping services, to disclose to the Company or any of its Affiliates such information and data as the Company or any such Affiliate shall request in order to facilitate the grant of Shares and the administration of the Plan; (ii) waives any data privacy rights he or she may have with respect to such information; and (iii) authorizes the Company and each Affiliate to store and transmit such information in electronic form.

[THE NEXT PAGE IS THE SIGNATURE PAGE]

IN WITNESS WHEREOF, the parties hereto have executed this Agreement as of the day and year first above written.

	IMMUNOGEN, INC.


	By:
	Name:
	Title:

	Non-Employee Director:


	Print Name:


	Print name: