This paper explores the effectiveness of public school-based mental health treatment for K-12 students. Extant clinical data from 2017- 2018 for behavioral health service recipients (n = 874) was used in this analysis. Relationships among clinical diagnosis at discharge, duration in treatment, student participation, and status of mental health improvement were examined. Logistic regression explored associations among variables of interest. Results indicate 74.3% (n = 649) of students were identified by clinicians with improvement in mental health status at discharge. The most prominent mental health diagnoses being treated in the schools were depression, anxiety, and trauma. Students involved in treatment were over 15 times more likely to be categorized as having an improved mental health status; students who lacked participation were 63% less likely to improve. Our results highlight the necessity for school administrators to prioritize and support school-based mental health services. The findings provide school administrators guidance, evidence, and impetus for implementing effective school-based mental health programs.