Schools are large providers of mental health services for children and adolescents. Recent educational policy initiatives at the federal level have ushered in Response to Intervention and school-wide behavior supports that have potential to involve teachers in school mental health interventions. Little research exists investigating the involvement of teachers in school mental health services or the level of efficacy associated with teachers providing these services. This paper conducts a systematic review to investigate the extent to which teachers a) are the primary school-based service providers, b) collaboratively work with other professionals to provide services, and c) what levels of interventions within the Response to Intervention (RTI) framework apply to these interventions. This paper further evaluates how efficacious teachers and school mental health professionals are in impacting outcomes in previous studies. Results indicated that out of the 49 school mental health studies analyzed, teachers were actively involved in 40.8% of mental health interventions evaluated, and were the sole providers of interventions in 18.4% of the studies. It was also found that many of these school mental health interventions were universal (Tier 1) and took place in the classrooms. Further examination of findings suggested that different personnel, such as school mental health professionals and teachers, achieved similar outcomes across the studies.