X0306 4 2020-03-02 0 0001370450 Willdan Group, Inc. WLDN 0001270606 BIEBER MICHAEL A 2401 EAST KATELLA AVENUE SUITE 300 ANAHEIM CA 92806 0 1 0 0 President Common Stock 2020-03-02 4 A 0 33300 0 A 57080 D Common Stock 2020-03-06 4 F 0 24154 32.68 D 32926 D Common Stock 2020-03-09 4 F 0 594 32.68 D 32332 D Common Stock 2020-03-10 4 D 0 976 28.05 D 31356 D Common Stock 2020-03-11 4 D 0 3394 24.71 D 27962 D Common Stock 2020-03-11 4 D 0 618 25.38 D 27344 D Represents performance-based restricted stock units previously granted to the Reporting Person by the Issuer on March 6, 2018. The performance conditions applicable to the award were determined to have been satisfied by the Issuer's Compensation Committee on March 2, 2020, resulting in the immediate vesting of the restricted stock units as to 33,300 shares of Common Stock. Includes an aggregate of 711 shares of Common Stock purchased under the Amended and Restated Willdan Group, Inc. 2006 Employee Stock Purchase Plan, including 430 shares on June 30, 2019 and 281 shares on December 31, 2019. Represents shares of the Issuer's Common Stock withheld for tax withholding purposes in connection with the vesting of the performance-based restricted stock units referenced in footnote (1). Represents shares of the Issuer's Common Stock withheld for tax withholding purposes in connection with the vesting of restricted stock on March 8, 2020, which restricted stock was granted on March 8, 2017. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $28.01 to $28.13 inclusive. The Reporting Person undertakes to provide to the Issuer, any security holder of the Issuer, or the staff of the Securities and Exchange Commission, upon request, full information regarding the number of shares sold at each separate price within the ranges set forth in footnotes (5), (6) and (7). The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $24.24 to $25.07 inclusive. The price reported in Column 4 is a weighted average price. These shares were sold in multiple transactions at prices ranging from $25.34 to $25.43 inclusive. /s/ Stacy McLaughlin, Attorney-in-fact for Michael A. Bieber 2020-03-12