“The Efficacy of CEQA Mitigation: Orange County Case Studies to Determine What Works” was released in December 2019. This study looks at the rate of success for mitigation measures on biological impacts. Twelve projects were reviewed across Orange County, including residential, mixed use, and infrastructure projects. Thanks to the collaboration with numerous agencies, cities, and developers, details on these projects were evaluated for their ability to meet measures adopted through the California Environmental Quality Act (CEQA) process. This particular study evaluates projects, their impacts, the mitigation measures, rate of success and/or failure, and provides recommendations for future study.