339 Community-Based Participatory Research as a Tool for Policy Change: A Case Study of the Southern California Environmental Justice Collaborative Dana Petersen 1 SRI International Meredith Minkler and Victoria Breckwich Vásquez University of California, Berkeley Andrea Corage Baden University of California, San Francisco Abstract In 2000, a regional rule governing maximum individual cancer risk from stationary facilities in South- ern California was dramatically altered, reducing allowable risk levels by 75%. This article uses a case study approach to explore the role of a community-based participatory research (CBPR) partnership, the Southern California Environmental Justice Collaborative, in producing research and helping spear- head policy advocacy leading to this policy change. It also highlights the role of the collaborative in helping to change the framing of the issue from individual to cumulative risk assessment, so that the regulatory agencies began to reflect this broader thinking in their policymaking. The collaborative’s structure and methodology, regional focus, relationships with key decision makers, and its reputation as an important source of both credible science and “people power” were seen as contributing to its effectiveness. The role of contextual factors including a recovering and more regulation-friendly economy also is highlighted, as are key barriers faced. Implications for other community–academic partnerships working to address regional and statewide public policy are discussed. Introduction When former President William J. Clinton signed Executive Order 12898 in 1994, close to a dozen federal agencies were charged with developing policies to address the disproportionate burden of pollution and other environmental hazards borne by communities of color and low-income communities in the United States (Shepard, Northridge, Prakash, & Stover, 2002). The president’s action was in part a response to environmental advocacy and activism in the United States that has achieved social movement proportions both in North America and internationally (Brugge & Hynes, 2005; Corburn, 2005; Shepard et al., 2002). An important component of the environmental justice movement has been its emphasis on involving community members in identifying issues in need of inves- tigation, collaborating in the conduct of the research, and translating research- based findings into action, including advocacy for policy level change. This approach, often termed community-based participatory research (CBPR) has received support from federal agencies including the National Institute for Envi- ronmental Health Sciences (NIEHS), the Environmental Protection Agency (EPA), and the Centers for Disease Control and Prevention (CDC); from philanthropic organizations (e.g., the W.K. Kellogg Foundation and The California Endowment), Review of Policy Research, Volume 23, Number 2 (2006) © 2006 by The Policy Studies Organization. All rights reserved.