School-level contextual factors have been found to influence reports of school climate. The purpose of the current study was to evaluate the extent to which these associations are related to the school climate traits being measured or the methods (i.e., informants) used to obtain them. Data from a multilevel multitrait-multimethod (MTMM) design in which structurally different and interchangeable students (n = 45,641) and teachers (n = 12,808), residing within 302 high schools, responded to items measuring four dimensions of school climate were evaluated through a multilevel correlated trait-correlated method (CT-CM) latent analysis that allowed for the estimation of both school-level trait and informant-based method factors. The resulting trait and method factors were regressed on several school-level contextual variables. Results indicated that the percentage of students receiving free and reduced-price meals (FRPM) in schools was associated with both school climate traits and informant-based method factors, school size and the percentage of minority students in schools were associated with some traits, and school size was associated with student method effects. Findings support the use of controlling for school-level contextual factors in school climate research.