Clark Williams-Derry directs research and outreach programs for Sightline Institute (formerly Northwest Environment Watch), a private, nonprofit research and communication center that seeks to foster a sustainable economy and way of life in the Pacific Northwest. Williams-Derry joined Sightline in 2001 to spearhead the Cascadia Scorecard project, Sightline's regional index of progress towards a sustainable Pacific Northwest.  Since then, he has authored more than a dozen Sightlne reports and conducted groundbreaking research in mapping and analyzing sprawl;  testing human breastmilk for toxics; and designing a regional climate cap-and-trade policy.

Before joining Sightline, Williams-Derry investigated federal farm and wetlands policy as a senior analyst at Environmental Working Group (EWG) in Washington, DC. While at EWG, he authored more than a dozen reports. He also oversaw the development of EWG's farm subsidy database, which has been credited with reframing the national debate on farm policy by the New York Times and other publications. Williams-Derry has spoken and consulted widely on sustainability issues.

Williams-Derry has also worked for the Seattle-based Earth Day Network and Grist Magazine, and as a researcher, legislative analyst, and media relations specialist for the National Audubon Society in Washington, DC. He graduated summa cum laude from Yale University in 1989 with a joint degree in mathematics and philosophy. A resident of Seattle's Ravenna neighborhood, Williams-Derry spends his "spare" time with his wife Amy and daughters Madeline and Eliza.