There is a significant drive in education to provide mental health supports in schools. One of the key approaches for this is through effective universal supports for students by implementing social and emotional learning (SEL). However, there has been little investigation of effective implementation accounting for the diversity of school environments. Through a secondary data analysis of an efficacy study for the Second Step curriculum, the current study assesses the role of environmental factors and the impact of student-teacher racial mismatch in implementation. The analysis uses a hierarchical linear modeling approach to assess both classroom and school level factors impact on effective implementation. The results demonstrate that environmental factors played little role in the effective implementation. Although mismatch did not impact the delivery of the curriculum, the results indicate significant difference in teachers' perception of students' engagement with the curriculum. Further analysis revealed interactional relationships with school level variables. Discussion of the implications of these findings along with future directions for research conclude this dissertation.