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These shares were sold in multiple transactions at prices ranging from $44.97 to $45.95, 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 this footnote (2) through footnote (11)."}],"balance_after":20310,"source":{"system":"sec-edgar","filing":"0001179110-21-003741","document":"edgar.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/1601038/000117911021003741/edgar.xml","form_type":"4"}},{"id":2792042,"issuer":{"id":4758,"kind":"organization","name":"Willdan Group, Inc.","symbol":"WLDN"},"owners":[{"id":86652,"kind":"person","name":"McLaughlin Stacy B.","position":1,"cik":"0001601038","reported_name":"McLaughlin Stacy B.","relationship":{"director":false,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"Chief Financial Officer"}}],"security":"Common Stock","published_at":"2021-03-12T17:08:46.000Z","date":"2021-03-10","kind":"grant","acquired":true,"shares":4588,"price":0,"value":0.0,"ownership":{"direct":true},"footnotes":[{"field":"shares","element":"transactionShares","label":"F1","text":"Represents performance-based restricted stock units previously granted to the Reporting Person by the Issuer on March 2, 2020. 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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."}],"balance_after":15035,"source":{"system":"sec-edgar","filing":"0001179110-20-007690","document":"edgar.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/1601038/000117911020007690/edgar.xml","form_type":"4"}},{"id":3111878,"issuer":{"id":4758,"kind":"organization","name":"Willdan Group, Inc.","symbol":"WLDN"},"owners":[{"id":86652,"kind":"person","name":"McLaughlin Stacy B.","position":1,"cik":"0001601038","reported_name":"McLaughlin Stacy B.","relationship":{"director":false,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"Chief Financial Officer"}}],"security":"Common Stock","published_at":"2020-06-12T16:01:51.000Z","date":"2020-06-10","kind":"grant","acquired":true,"shares":9816,"price":0,"value":0.0,"ownership":{"direct":true},"footnotes":[{"field":"shares","element":"transactionShares","label":"F1","text":"Represents performance-based restricted stock units previously granted to the Reporting Person by the Issuer on June 13, 2019. 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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 7,010 shares of Common Stock."},{"field":"balance_after","element":"sharesOwnedFollowingTransaction","label":"F2","text":"Includes an aggregate of 706 shares of Common Stock purchased under the Amended and Restated Willdan Group, Inc. 2006 Employee Stock Purchase Plan, including 366 shares on June 30, 2019 and 340 shares on December 31, 2019."}],"balance_after":13341,"source":{"system":"sec-edgar","filing":"0001179110-20-003573","document":"edgar.xml","document_sequence":1,"table":"nonDerivative","row_type":"transaction","position":1,"url":"https://www.sec.gov/Archives/edgar/data/1601038/000117911020003573/edgar.xml","form_type":"4"}},{"id":3536482,"issuer":{"id":4758,"kind":"organization","name":"Willdan Group, 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The first and second installments became exercisable on each of November 5, 2015 and November 5, 2016, and the third installment will become exercisable on November 5, 2017."}],"balance_after":1667,"derivative":{"exercise_price":14.01,"expiration_date":"2024-11-05","underlying":"Common Stock","underlying_shares":3333},"source":{"system":"sec-edgar","filing":"0001179110-17-004766","document":"edgar.xml","document_sequence":1,"table":"derivative","row_type":"transaction","position":9,"url":"https://www.sec.gov/Archives/edgar/data/1601038/000117911017004766/edgar.xml","form_type":"4"}},{"id":4382430,"issuer":{"id":4758,"kind":"organization","name":"Willdan Group, Inc.","symbol":"WLDN"},"owners":[{"id":86652,"kind":"person","name":"McLaughlin Stacy B.","position":1,"cik":"0001601038","reported_name":"McLaughlin Stacy B.","relationship":{"director":false,"officer":true,"ten_percent_owner":false,"other":false,"officer_title":"Chief Financial Officer"}}],"security":"Stock Option (Right to Buy)","published_at":"2017-03-16T21:48:18.000Z","date":"2017-03-14","kind":"exercise","acquired":false,"shares":5000,"price":0,"value":0.0,"ownership":{"direct":true},"footnotes":[{"field":"derivative.exercise_date","element":"exerciseDate","label":"F6","text":"The option, representing a right to purchase a total of 15,000 shares, becomes completely exercisable in three equal installments. 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