Study assessments were completed by youth and parents online through Research Electronic Data Capture,17 (link) a secure web-based data collection platform, at baseline before treatment allocation (T1), after completion of the 8-week intervention (immediately after treatment) (T2), and at 3-month follow-up (T3). As part of their assessments, youth completed online diaries through Research Electronic Data Capture for 7 days at each assessment period. Study staff contacted youth about completion of assessments only; both the app and web program include automated reminders to log in and complete intervention tasks. We provided gift card incentives after completion of each of the 3 study assessments.