A positive school climate is characterized by a supportive, orderly, and fair interpersonal climate. Children's perceptions of interpersonal climate and school safety are associated with several academic and behavioral adjustment outcomes. The current study has two goals: (1) to better understand the contribution of school interpersonal climate to children's school success; and (2) to examine whether the impact of the whole-school implementation of social and character development (SACD) programs are moderated by interpersonal climate. The study asks: (1) Is there a direct relationship between school interpersonal climate at the start of 3rd grade as perceived by children and teachers and modeled at the individual and school levels and children's school engagement and academic competence/motivation at the end of 5th grade?; (2) Do school-aggregated child and teacher perceptions of interpersonal climate moderate the relationship between children's individual perceptions of climate and the outcomes?; (3) Is there an impact of SACD programs on engagement and academic competence?; and (4) Do school-aggregated child and teacher perceptions of interpersonal climate moderate the impact of SACD programs on school engagement and academic competence? This study used data from a three-year, multi-site, school-randomized evaluation of Social and Character Development (SACD) Programs in 83 elementary schools in 7 sites and 6 states funded by the Institute of Education Sciences (IES) and Centers for Disease Control. The child sample consisted of 4,245 children in 320 classrooms at baseline. In each site, a research team randomized 10 to 18 schools to the business-as-usual approach to implement the SACD program. The randomization employed a matched pair design with stratified sampling. As part of the evaluation, a common set of student outcomes including social and emotional competence, behavior, academics, and perceptions of school climate were collected across sites. Data included survey data from students, primary caregivers, teachers, and interview responses from principals. In addition, each site collected its own set of site-specific data. Three-level hierarchical linear modeling with fixed effects in which children were nested in teachers and schools was used to account for the multilevel nature of the data. Findings reveal that: (1) children who experienced a lack of community were less engaged and had more difficulty academically; (2) teachers' perceptions of support and safety in school were also related to academic outcomes; (3) cross-level interaction pointed to the importance of considering the fit between the child and the school environment--children who had a good fit (i.e., perceived a more negative climate in the context of a school with a more negative climate) actually reported being more engaged, compared to children who had a poor fit (i.e., perceived a negative climate in the context of a less negative climate); and (4) SACD programs did not directly improve academic outcomes. Limitations of this study include low intraclass correlations and reliabilities at the school levels for the study outcomes, suggesting low power to detect group-level effects. Tables and figures are appended. [For the IES NCER report on SACD Programs that provided data for this study, see ED512329.].