Cascadia convened, facilitated, and managed the Biodiversity, Species, and Food Webs Topic Forum to inform the development of the Puget Sound Partnership’s 2020 Action Agenda. Cascadia facilitated the meetings of a work group of regional scientific and policy experts, and assisted with outreach at the public Topic Forum meeting. We prepared four short memos synthesizing existing information and approaches to biodiversity issues in Puget Sound, identifying gaps in current efforts, and providing input on priorities. We later revised these memos in response to both Work Group and public comments, and they served as source material for development of the Action Agenda.