Willdan Group, Inc. is an American publicly traded company selling professional technical and consulting services to public and private utilities, public agencies at all levels of government, and commercial and industrial firms. The company operates offices in more than a dozen states, with its key operations in California and New York. In 1964, the company was built by William Stookey and Dan Heil in southern California on a then-unique model of providing outsourced engineering services exclusively to municipalities, especially newly urbanizing cities. Over the next 50 years, the company's expansion has reflected the increasingly complex challenges facing communities, with a forward-looking focus on energy efficiency, energy engineering, cogeneration, Energy Savings Performance Contract, Community Choice Aggregation, smart city, microgrid consulting, and Transactive energy software. In 2006, Willdan Group, Inc. completed its initial public offerings in NASDAQ, becoming a publicly traded company under the symbol WLDN. In 2008, Willdan acquired Intergy Corporation, then renamed Willdan Energy Solutions, offering energy efficiency utility program management. In 2015, Willdan acquired 360 Energy Engineers and Abacus Resource Management, expanding its capabilities into Energy Service Company and Energy Savings Performance Contract services. Willdan acquired NYC-based Genesys Engineering, P.C., in 2016, bringing Power Engineering services into its portfolio, with an eye to evolution of U.S. power systems toward Distributed generation and microgrids.