This study explored parent engagement in an evidence-based treatment, the Cognitive Behavioral Intervention for Trauma in Schools (CBITS), which was delivered in a school setting. To examine the successes and challenges in engaging parents in this school-based program, we conducted qualitative interviews by phone to obtain data from clinicians, parents, and other school personnel across eleven schools from 3 different regions of the United States. Almost all of these schools served low-income and ethnically diverse communities. We describe general impressions of parent engagement, parent reactions and preferences with regard to CBITS, barriers to parent engagement, and how to overcome barriers from multiple perspectives. Parent engagement across schools varied, with extensive outreach and relatively good parent engagement in CBITS described in some schools, while in other schools, efforts to engage parents were not as consistent. Implications for future efforts to engage parents in school-based treatments are discussed.