UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13D

(Rule 13d-101)

INFORMATION TO BE INCLUDED IN STATEMENTS FILED PURSUANT

TO § 240.13d-1(a) AND AMENDMENTS THERETO FILED PURSUANT TO

§ 240.13d-2(a)

(Amendment No. 22)1

Adaptec, Inc.

(Name of Issuer)

Common Stock, par value $0.001

(Title of Class of Securities)

00651F108

(CUSIP Number)

Warren G. Lichtenstein

Steel Partners Holdings L.P.

590 Madison Avenue, 32nd Floor

New York, New York 10022

(212) 520-2300

(Name, Address and Telephone Number of Person

Authorized to Receive Notices and Communications)

June 10, 2010

(Date of Event Which Requires Filing of This Statement)

If the filing person has previously filed a statement on Schedule 13G to report the acquisition that is the subject of this Schedule 13D, and is filing this schedule because of §§ 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g), check the following box ¨.

Note:  Schedules filed in paper format shall include a signed original and five copies of the schedule, including all exhibits.  See § 240.13d-7 for other parties to whom copies are to be sent.

_______________

1              The remainder of this cover page shall be filled out for a reporting person’s initial filing on this form with respect to the subject class of securities, and for any subsequent amendment containing information which would alter disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed to be “filed” for the purpose of Section 18 of the Securities Exchange Act of 1934 (“Act”) or otherwise subject to the liabilities of that section of the Act but shall be subject to all other provisions of the Act (however, see the Notes).

CUSIP NO. 00651F108

1	NAME OF REPORTING PERSON STEEL PARTNERS II, L.P.
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP		(a) o   (b) o
3	SEC USE ONLY
4	SOURCE OF FUNDS WC
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) OR 2(e)		¨
6	CITIZENSHIP OR PLACE OF ORGANIZATION DELAWARE
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH	7	SOLE VOTING POWER - 0 -
	8	SHARED VOTING POWER 27,722,277
	9	SOLE DISPOSITIVE POWER - 0 -
	10	SHARED DISPOSITIVE POWER 27,722,277
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 27,722,277
12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES		o
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 23.0%
14	TYPE OF REPORTING PERSON PN

2

CUSIP NO. 00651F108

1	NAME OF REPORTING PERSON STEEL PARTNERS HOLDINGS L.P.
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP		(a) o   (b) o
3	SEC USE ONLY
4	SOURCE OF FUNDS AF
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) OR 2(e)		¨
6	CITIZENSHIP OR PLACE OF ORGANIZATION DELAWARE
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH	7	SOLE VOTING POWER - 0 -
	8	SHARED VOTING POWER 27,722,277
	9	SOLE DISPOSITIVE POWER - 0 -
	10	SHARED DISPOSITIVE POWER 27,722,277
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 27,722,277
12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES		o
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 23.0%
14	TYPE OF REPORTING PERSON PN

3

CUSIP NO. 00651F108

1	NAME OF REPORTING PERSON STEEL PARTNERS LLC
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP		(a) o   (b) o
3	SEC USE ONLY
4	SOURCE OF FUNDS AF
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) OR 2(e)		¨
6	CITIZENSHIP OR PLACE OF ORGANIZATION DELAWARE
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH	7	SOLE VOTING POWER - 0 -
	8	SHARED VOTING POWER 27,722,277
	9	SOLE DISPOSITIVE POWER - 0 -
	10	SHARED DISPOSITIVE POWER 27,722,277
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 27,722,277
12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES		o
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 23.0%
14	TYPE OF REPORTING PERSON OO

4

CUSIP NO. 00651F108

1	NAME OF REPORTING PERSON WARREN G. LICHTENSTEIN
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP		(a) o   (b) o
3	SEC USE ONLY
4	SOURCE OF FUNDS AF
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) OR 2(e)		¨
6	CITIZENSHIP OR PLACE OF ORGANIZATION USA
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH	7	SOLE VOTING POWER - 0 -
	8	SHARED VOTING POWER 27,722,277
	9	SOLE DISPOSITIVE POWER - 0 -
	10	SHARED DISPOSITIVE POWER 27,722,277
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 27,722,277
12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES		o
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 23.0%
14	TYPE OF REPORTING PERSON IN

5

CUSIP NO. 00651F108

1	NAME OF REPORTING PERSON JACK L. HOWARD
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP		(a) o   (b) o
3	SEC USE ONLY
4	SOURCE OF FUNDS OO
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) OR 2(e)		¨
6	CITIZENSHIP OR PLACE OF ORGANIZATION USA
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH	7	SOLE VOTING POWER 37,500 *
	8	SHARED VOTING POWER - 0 -
	9	SOLE DISPOSITIVE POWER 25,000 **
	10	SHARED DISPOSITIVE POWER - 0 -
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 37,500 *
12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES		o
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) LESS THAN 1%
14	TYPE OF REPORTING PERSON IN

* Represents 18,750 Shares underlying Restricted Stock Awards, 6,250 Shares of which have vested, and 18,750 Shares underlying Non-Qualified Stock Options that are exercisable within 60 days of the date hereof.

** Represents 6,250 Shares underlying Restricted Stock Awards that have vested and 18,750 Shares underlying Non-Qualified Stock Options that are exercisable within 60 days of the date hereof.

6

CUSIP NO. 00651F108

1	NAME OF REPORTING PERSON JOHN J. QUICKE
2	CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP		(a) o   (b) o
3	SEC USE ONLY
4	SOURCE OF FUNDS OO
5	CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED PURSUANT TO ITEM 2(d) OR 2(e)		¨
6	CITIZENSHIP OR PLACE OF ORGANIZATION USA
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH	7	SOLE VOTING POWER 37,500 *
	8	SHARED VOTING POWER - 0 -
	9	SOLE DISPOSITIVE POWER 25,000 **
	10	SHARED DISPOSITIVE POWER - 0 -
11	AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON 37,500 *
12	CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN SHARES		o
13	PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) LESS THAN 1%
14	TYPE OF REPORTING PERSON IN

* Represents 18,750 Shares underlying Restricted Stock Awards, 6,250 Shares of which have vested, and 18,750 Shares underlying Non-Qualified Stock Options that are exercisable within 60 days of the date hereof.

** Represents 6,250 Shares underlying Restricted Stock Awards that have vested and 18,750 Shares underlying Non-Qualified Stock Options that are exercisable within 60 days of the date hereof.

7

CUSIP NO. 00651F108

The following constitutes Amendment No. 22 to the Schedule 13D filed by the undersigned (“Amendment No. 22”).  This Amendment No. 22 amends the Schedule 13D as specifically set forth.

Item 3. Source and Amount of Funds or Other Consideration.

Item 3 is hereby amended and restated to read as follows:

The aggregate purchase price of the 27,722,277 Shares owned by Steel Partners II is approximately $90,019,990, including brokerage commissions.  The Shares owned by Steel Partners II were acquired with partnership funds.

The Shares beneficially owned by Messrs. Howard and Quicke were awarded to them in their capacities as directors of the Issuer.

Set forth on Schedule B annexed to Amendment No. 21 to the Schedule 13D (“Schedule B”) is the aggregate purchase price of the Shares beneficially owned, if any, by each of the directors of Steel Holdings GP.

Steel Partners II effects purchases of securities primarily through margin accounts maintained for it with prime brokers, which may extend margin credit to it as and when required to open or carry positions in the margin accounts, subject to applicable federal margin regulations, stock exchange rules and the prime brokers’ credit policies.  In such instances, the positions held in the margin accounts are pledged as collateral security for the repayment of debit balances in the accounts.

Item 5. Interest in Securities of the Issuer.

Item 5(a) is hereby amended and restated to read as follows:

(a)           The aggregate percentage of Shares reported owned by each person named herein is based upon 120,396,971 Shares outstanding, which is the total number of Shares outstanding as of May 12, 2010 as reported in the Issuer’s Form 10-K filed with the Securities and Exchange Commission on May 27, 2010.

As of the close of business on June 11, 2010, Steel Partners II owned directly 27,722,277 Shares, constituting approximately 23.0% of the Shares outstanding.  By virtue of their relationships with Steel Partners II discussed in further detail in Item 2, each of Steel Holdings, Partners LLC and Warren G. Lichtenstein may be deemed to beneficially own the Shares owned by Steel Partners II.

As of the close of business on June 11, 2010, Jack L. Howard beneficially owned 18,750 Shares underlying Restricted Stock Awards, 6,250 Shares of which have vested, and beneficially owned an additional 18,750 Shares underlying Non-Qualified Stock Options that are exercisable within 60 days of the date hereof, constituting in the aggregate less than 1% of the Shares outstanding.

As of the close of business on June 11, 2010, John J. Quicke beneficially owned 18,750 Shares underlying Restricted Stock Awards, 6,250 Shares of which have vested, and beneficially owned an additional 18,750 Shares underlying Non-Qualified Stock Options that are exercisable within 60 days of the date hereof, constituting in the aggregate less than 1% of the Shares outstanding.

8

CUSIP NO. 00651F108

Set forth on Schedule B is the aggregate number and percentage of Shares beneficially owned, if any, by each of the directors of Steel Holdings GP.  Unless otherwise indicated thereon, each of the persons listed on Schedule B has (i) the sole power to vote and dispose of the Shares they beneficially own, if any, and (ii) the right to receive, or the power to direct the receipt of dividends from, or proceeds from the sale of, the Shares that they beneficially own, if any.

Each of the Reporting Persons, as a member of a “group” with the other Reporting Persons for purposes of Rule 13d-5(b)(1) of the Securities Exchange Act of 1934, as amended (the “Exchange Act”), may be deemed to beneficially own the Shares owned by the other Reporting Persons.

Item 5(c) is hereby amended to add the following:

(c)           Schedule C annexed hereto lists all transactions in the Shares by the Reporting Persons since the filing of Amendment No. 21 to the Schedule 13D.  All of such transactions were effected in the open market.

Item 6. Contracts, Arrangements, Understandings or Relationships With Respect to Securities of the Issuer.

Item 6 is hereby amended to add the following:

On June 11, 2010, Steel Partners II entered into a Purchase Trading Plan Agreement (the “Agreement”) with Mutual Securities, Inc., a registered broker-dealer, for the purpose of establishing a trading plan to effect purchases of Shares of the Issuer beginning on June 21, 2010 in compliance with all applicable laws, including, without limitation, Section 10(b) of the Securities Exchange Act of 1934, as amended, and the rules and regulations promulgated thereunder, including, but not limited to, Rule 10b5-1.  A copy of the Agreement is attached hereto as Exhibit 99.1 and is incorporated herein by reference.

Item 7. Material to be Filed as Exhibits.

Item 7 is hereby amended to add the following exhibit:

99.1           Purchase Trading Plan Agreement by and between Steel Partners II, L.P. and Mutual Securities, Inc., dated June 11, 2010.

9

CUSIP NO. 00651F108

SIGNATURES

After reasonable inquiry and to the best of his knowledge and belief, each of the undersigned certifies that the information set forth in this statement is true, complete and correct.

Dated:  June 14, 2010	STEEL PARTNERS II, L.P.
	By:		Steel Partners II GP LLC General Partner
	By:	/s/ Sanford Antignas
		Sanford Antignas Chief Operating Officer

STEEL PARTNERS HOLDINGS L.P.
By:		Steel Partners Holdings GP LLC General Partner
By:	/s/ Sanford Antignas
	Sanford Antignas Chief Operating Officer

STEEL PARTNERS LLC
By:	/s/ Sanford Antignas
	Sanford Antignas Chief Operating Officer

/s/ Sanford Antignas

SANFORD ANTIGNAS

as Attorney-In-Fact for Warren G. Lichtenstein

/s/ Jack L. Howard

JACK L. HOWARD

/s/ Sanford Antignas

SANFORD ANTIGNAS

as Attorney-In-Fact for John J. Quicke

10

CUSIP NO. 00651F108

SCHEDULE C

Transactions in the Securities of the Issuer

Since the Filing of Amendment No. 21 to the Schedule 13D

Class of Security Securities Purchased Price ($) Date of Purchase

STEEL PARTNERS II, L.P.

Common Stock	177,596	3.0027	06/08/10
Common Stock	103,700	3.0000	06/08/10
Common Stock	215,000	3.0000	06/08/10
Common Stock	414,320	3.0288	06/09/10
Common Stock	86,300	3.0100	06/09/10
Common Stock	25,000	3.0300	06/09/10
Common Stock	758,352	3.0500	06/10/10
Common Stock	100,000	3.0500	06/10/10
Common Stock	558,552	3.0500	06/10/10
Common Stock	5,000	3.0300	06/11/10
Common Stock	63,600	3.0500	06/11/10