INTRODUCTION: Adverse childhood experiences (ACEs) are strongly correlated with many of the most common causes of preventable illness, preventable death, and health disparities. In January 2020, California launched the first statewide initiative to integrate ACE screening throughout its Medicaid system. A key element of the initiative was the California ACEs Learning and Quality Improvement Collaborative, a 48-clinic, 16-month learning collaborative. This evaluation aimed to determine whether developing a trauma-informed environment of care was associated with uptake of ACE screening. METHODS: Participants included 40 of 48 clinics that participated in the statewide learning collaborative. Clinics completed an assessment of progress in 5 essential components of trauma-informed health care at baseline and 1-year follow-up. Clinics tracked data on ACE screens completed on an ongoing basis and submitted data quarterly. A hierarchical linear model was used to examine the association between change in readiness for trauma-informed health care and change in quarterly screens. RESULTS: Readiness for trauma-informed health care increased for all participating clinics over the course of the learning collaborative. The average number of quarterly screens also increased, with considerable variability among clinics. Clinics with larger increases in readiness for trauma-informed health care had larger increases in quarterly screens. DISCUSSION: The findings align with long-standing recommendations for trauma screening to occur in the context of trauma-informed environments of care. CONCLUSION: A trauma-informed clinic is the foundation for successful adoption of ACE screening. ACE screening initiatives should include education and sufficient support for clinics to embrace a trauma-informed systems change process.