The Positive Outcomes With Emotion Regulation (POWER) Program is a transdiagnostic intervention for adolescents at risk of developing emotional disorders. The POWER Program was designed to be implemented in secondary schools, by school personnel with or without specialized mental health training, as a Tier 2 intervention. In this pilot study, the POWER Program was implemented by school psychologists and school psychologists-in-training and evaluated across four focal student participants using a multiple-baseline-across-participants single-case design. Program efficacy was assessed using systematic direct classroom observations of student negative affect and social engagement as well as student and caregiver ratings of emotional and behavioral symptoms. Program usability was assessed through rating scales completed by intervention facilitators and student participants. Overall, results provide evidence of the POWER Program's small- to large-sized effects on students' emotional and behavioral functioning as observed in the classroom and self-reported by students. In addition, results suggest implementation facilitators' and students' positive impressions of the program, evident in ratings of high understanding, feasibility, and acceptability across groups. Study limitations are highlighted with attention to opportunities to further refine and evaluate the POWER Program.