PURPOSE To understand clinician and clinical staff perspectives on the implementation of routine Adverse Childhood Experience (ACE) screening in pediatric primary care. METHODS We conducted a qualitative evaluation in 5 clinics in Los Angeles County, California, using 2 rounds of focus group discussions: during an early phase of the initiative, and 7 months later. In the first round, we conducted 14 focus group discussions with 67 participants. In the second round, we conducted 12 focus group discussions with 58 participants. Participants comprised clinic staff involved in ACE screening, including frontline staff that administer the screening, medical clinicians that use screening to counsel patients and make referrals, and psychosocial support staff who may receive referrals. RESULTS Themes were grouped into 3 categories: (1) screening acceptability and perceived utility, (2) implementation and quality improvement, and (3) effects of screening on patients and clinicians. Regarding scr