Previous studies indicate that school climate is important for student health and academic achievement. This study concerns the validity and reliability of the student edition a Swedish instrument for measuring pedagogical and social school climate (PESOC). Data were collected from 5,745 students at 97 Swedish secondary schools. Multilevel confirmatory factor analyses were conducted, and multilevel composite reliability estimates, as well as correlations with school-level achievement indicators, were calculated. The results supported an 8-factor structure at the student level and 1 general factor at the school level. Factor loadings and composite reliability estimates were acceptable at both levels. The school-level factor was moderately and positively correlated with school-level academic achievement. The student PESOC is a promising instrument for studying school climate.