School mental health (SMH) services are widespread but are often not well integrated into school settings, based on evidence for effectiveness, or efficiently delivered. This paper presents results of a pilot study of a brief (4 session) assessment, engagement, triage, and initial intervention strategy for SMH clinicians working in high schools. The study included n = 29 students served by five clinicians trained on the Brief Intervention for School Clinicians (BRISC), compared to n = 37 students served by 10 similar clinicians providing school-based services as usual. Clinicians implemented BRISC elements with good fidelity and reported the strategy was feasible and aligned with student needs. BRISC students reported greater satisfaction and therapeutic alliance. No differences were found for overall behavioral functioning; however, BRISC students showed greater reduction in depression and anxiety symptoms. Academic outcomes were not associated with condition. After four sessions, the majority of BRISC students were discharged without need for continued services, suggesting it could promote efficiency. Results indicate that BRISC is a promising approach that merits further research.