Objective: To evaluate the effectiveness of 2 brief school-based interventions targeting the homework problems of adolescents with attention-deficit/hyperactivity disorder (ADHD)—the Homework, Organization, and Planning Skills (HOPS) intervention and the Completing Homework by Improving Efficiency and Focus (CHIEF) intervention, as implemented by school mental health providers during the school day. A secondary goal was to use moderator analyses to identify student characteristics that may differentially predict intervention response. Method: Two-hundred and eighty middle school students with ADHD were randomized to the HOPS or CHIEF interventions or to waitlist, and parent and teacher ratings were collected pre, post, and at a 6-month follow-up. Results: Both interventions were implemented with fidelity by school mental health providers. Participants were pulled from elective periods and sessions averaged less than 20 min. Participants in HOPS and CHIEF demonstrated significantly greater improvements in comparison with waitlist on parent ratings of homework problems and organizational skills and effect sizes were large. HOPS participants also demonstrated moderate effect size improvements on materials management and organized action behaviors according to teachers. HOPS participants made significantly greater improvements in parent- and teacher-rated use of organized actions in comparison with CHIEF, but not on measures of homework problems. Moderation analyses revealed that participants with more severe psychopathology and behavioral dysregulation did significantly better with the HOPS intervention as compared to the CHIEF intervention. Conclusions: Brief school-based interventions implemented by school providers can be effective. This type of service delivery model may facilitate overcoming the oft cited research-to-practice gap.