This study tested an integrated package for high-quality school mental health (SMH) services involving quality assessment and improvement, family engagement and empowerment, modular evidence-based practice, and implementation support. Within a two-year randomized controlled trial, 35 clinicians, who provided services to 529 students and their families, were randomly assigned to the enhanced quality assessment and improvement intervention condition and a comparison condition focused on promoting personal and staff wellness. Significant clinician-level findings were found for increased use and fidelity of evidence-based practices and greater use of structured assessments and sessions involving family members. Results are discussed in relation to needed methodological improvements in SMH treatment outcome research and increasing use of evidence-based practices by clinicians by adding accountability and incentives to training, coaching, and implementation support.