UNITED STATES
SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

SCHEDULE 13G

Under the Securities Exchange Act of 1934
(Amendment No. 1)*

Plug Power Inc.


(Name of Issuer)

Common Stock


(Title of Class of Securities)

72919P202


(CUSIP Number)

December 31, 2012


(Date of Event which Requires Filing of this Statement)

Check the appropriate box to designate the rule pursuant to which this Schedule is filed:

[X] Rule 13d-1(b)
[   ] Rule 13d-1(c)
[   ] Rule 13d-1(d)

* 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 the disclosures provided in a prior cover page.

The information required in 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 Instructions).

CUSIP No.: 72919P202
1 NAME OF REPORTING PERSON
Robeco Investment Management, Inc

I.R.S. IDENTIFICATION NO. OF ABOVE PERSON (ENTITIES ONLY)
98-0202744
2 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP
(a)  [   ]
(b)  [   ]
3 SEC USE ONLY
 
4 CITIZENSHIP OR PLACE OF ORGANIZATION
Delaware
NUMBER OF SHARES BENEFICIALLY OWNED BY EACH REPORTING PERSON WITH 5 SOLE VOTING POWER
3,573,185
6 SHARED VOTING POWER
0
7 SOLE DISPOSITIVE POWER
3,573,185
8 SHARED DISPOSITIVE POWER
0
9 AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
3,573,185
10 CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (9) EXCLUDES CERTAIN SHARES []

11 PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (9)
9.37%
12 TYPE OF REPORTING PERSON
IA

CUSIP No.: 72919P202
ITEM 1(a). NAME OF ISSUER:
Plug Power Inc.
ITEM 1(b). ADDRESS OF ISSUER'S PRINCIPAL EXECUTIVE OFFICES:
968 Albany Shaker Road
Latham, NY 12110
ITEM 2(a). NAME OF PERSON FILING:
Robeco Investment Management, Inc
ITEM 2(b). ADDRESS OF PRINCIPAL BUSINESS OFFICE OR, IF NONE, RESIDENCE:
One Beacon St.
Boston, MA 02108
ITEM 2(c). CITIZENSHIP:
Delaware
ITEM 2(d). TITLE OF CLASS OF SECURITIES:
Common Stock
ITEM 2(e). CUSIP NUMBER:
72919P202
ITEM 3. IF THIS STATEMENT IS FILED PURSUANT TO SECTION 240.13d-1(b), or 13d-2(b) or (c) CHECK WHETHER THE PERSON FILING IS A:
(a) [   ]  Broker or dealer registered under Section 15 of the Act (15 U.S.C. 78c);
(b) [   ]  Bank as defined in Section 3(a)(6) of the Act (15 U.S.C. 78c);
(c) [   ]  Insurance company as defined in Section 3(a)(19) of the Act (15 U.S.C. 78c);
(d) [   ]  Investment company registered under Section 8 of the Investment Company Act of 1940
(15 U.S.C 80a-8);
(e) [X]  An investment adviser in accordance with 240.13d-1(b)(1)(ii)(E);
(f) [   ]  An employee benefit plan or endowment fund in accordance with 240.13d-1(b)(1)(ii)(F);
(g) [   ]  A parent holding company or control person in accordance with 240.13d-1(b)(1)(ii)(G);
(h) [   ]  A savings associations as defined in Section 3(b) of the Federal Deposit Insurance Act
(12 U.S.C. 1813);
(i) [   ]  A church plan that is excluded from the definition of an investment company under Section 3(c)(14) of the Investment Company Act of 1940 (15 U.S.C. 80a-3);
(j) [   ]  A non-U.S. institution in accordance with 240.13d-1(b)(1)(ii)(J);
(k) [   ]  Group, in accordance with 240.13d-1(b)(1)(ii)(K). If filing as a non-U.S. institution
in accordance with 240.13d1(b)(1)(ii)(J), please specify the type of institution:
ITEM 4. OWNERSHIP:
Provide the following information regarding the aggregate number and percentage of the class of securities of the issuer identified in Item 1.
(a) Amount beneficially owned:
3,573,185
(b) Percent of class:
9.37%
(c) Number of shares as to which the person has:
(i)   Sole power to vote or to direct the vote:
3,573,185
(ii)  Shared power to vote or to direct the vote:
0
(iii) Sole power to dispose or to direct the disposition of:
3,573,185
(iv) Shared power to dispose or to direct the disposition of:
0
ITEM 5. OWNERSHIP OF FIVE PERCENT OR LESS OF A CLASS:
If this statement is being filed to report the fact that as of the date hereof the reporting person has ceased to be the beneficial owner of more than five percent of the class of securities, check the following [   ].
ITEM 6. OWNERSHIP OF MORE THAN FIVE PERCENT ON BEHALF OF ANOTHER PERSON:
This Schedule is being filed with respect to 3,573,185 shares Plug Power Inc. (the Common Stock) held by Robeco Investment Management, Inc. (RIM) on 12/31/2012 for the discretionary account of its client, the Robeco Boston Partners Long/Short Equity Fund of The RBB Fund, Inc.. By Reason of rule 13d-3 under the act RIM may be deemed to be a beneficial owner of such shares. Robeco Investment Management, Inc. (RIM) on behalf of its clients has or may have the right to receiver the power to direct their receipt of dividends from, or the proceeds from the sale of, securities held in their accounts. Clients on whose behalf that RIM is known to have such right or power with respect to more than 5% of the class of securities to which this report relates are: Robeco Boston Partners Long/Short Equity Fund of The RBB Fund, Inc 
ITEM 7. IDENTIFICATION AND CLASSIFICATION OF THE SUBSIDIARY WHICH ACQUIRED THE SECURITY BEING REPORTED ON BY THE PARENT HOLDING COMPANY:
Not applicable. 
ITEM 8. IDENTIFICATION AND CLASSIFICATION OF MEMBERS OF THE GROUP:
Not applicable. 
ITEM 9. NOTICE OF DISSOLUTION OF GROUP:
Not applicable. 
ITEM 10. CERTIFICATION:
By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect.

SIGNATURE

After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct.
Date
Robeco Investment Management, Inc
/s/ Liana Safanov

Signature
Liana Safanov, Compliance Officer

Name/Title



Attention: Intentional misstatements or omissions of fact constitute Federal criminal violations (see 18 U.S.C. 1001).