UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

FORM 8-K

CURRENT REPORT

PURSUANT TO SECTION 13 OR 15(D) OF THE

SECURITIES EXCHANGE ACT OF 1934

Date of Report (Date of earliest event reported): October 10, 2011

NORTHWEST PIPE COMPANY

(Exact name of registrant as specified in its charter)

5721 SE Columbia Way, Suite 200

Vancouver, WA 98661

(360) 397-6250

(Address, including zip code, and telephone number, including

area code, of registrant’s principal executive offices)

Check the appropriate box below if the Form 8-K filing is intended to simultaneously satisfy the filing obligation of the registrant under any of the following provisions:

On October 10, 2011, the Board of Directors of Northwest Pipe Company (the “Company”), upon the recommendation of the Compensation Committee, approved grants of restricted stock units (“RSUs”) and performance share units (“PSUs”) for the following Executive Officers of the Company, as well as other senior members of management, in the amounts set forth below. Pursuant to these long-term incentive grants, each Executive Officer or other senior member of management received an award of RSUs and PSUs valued at an amount equal to a specific percentage of his or her respective annual base salary, with 29 percent of each award represented by RSUs and 71 percent of each award represented by PSUs. The RSUs awarded will vest based upon continued service with the Company as follows: 66.7 percent will vest on January 1, 2013 and 33.3 percent will vest on January 1, 2014. The PSUs awarded will vest as follows: 17 percent will vest based on the Company’s performance against strategic goals before January 1, 2012; 56 percent will vest on January 1, 2013 based on the Company’s total shareholder return for 2011 and 2012 as compared with a specified group of peer companies; and 27 percent will vest on January 1, 2014 based on the Company’s total shareholder return for 2011, 2012 and 2013 as compared with a specified group of peer companies. The actual number of PSUs which will vest will be determined based on the performance level achieved and may be equal to, greater than, or less than the number of PSUs specified below. In the event of a “change in control” (as defined in the Agreements), vesting will be accelerated pro rata to reflect time elapsed and performance to date. The foregoing descriptions of the terms of the RSU and PSU awards are qualified by reference to the full text of the forms of Restricted Stock Unit Agreement and Performance Share Unit Agreement (the “Agreements”), which are filed herewith as Exhibits 10.1 and 10.2 and incorporated herein by reference.

SIGNATURE

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized on October 12, 2011.