X0306 4 2020-06-19 0 0001370450 Willdan Group, Inc. WLDN 0001452377 Chow Daniel 2401 EAST KATELLA AVE SUITE 300 ANAHEIM CA 92806 0 1 0 0 Chief Operating Officer Common Stock 2020-06-19 4 S 0 4832 23.52 D 55530 D Represents shares of Common Stock sold in the open market, the proceeds of which were used to pay the tax withholding obligations incurred upon the vesting of performance-based restricted stock units on June 10, 2020. The price reported in Column 4 is the weighted average price. These shares were sold in multiple transactions at prices ranging from $23.50 to $24.11, inclusive. The reporting person undertakes to provide to Willdan Group, Inc., any security holder of Willdan Group, Inc., 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 range set forth above. Includes 889 shares of restricted stock that vest on October 31, 2020. /s/ Stacy McLaughlin, Attorney-in-fact for Daniel Chow 2020-06-22