The structure of perceived school climate and the relationship of climate dimensions to adaptation were examined in a large-scale multiyear investigation of students who attend middle-grade-level schools. Analyses of the structure, reliability, interrater convergence, and stability of school climate ratings were conducted in a large-scale sample of over 105,000 students in 188 schools. The climate scales exhibited a stable dimensional structure, high levels of internal consistency, and moderate levels of stability over 1-and 2-year time intervals. The relationship between climate ratings and students' adjustment was examined in 3 increasingly large samples of schools and students that were collected during successive years of this project. Ratings of multiple climate dimensions were associated consistently with indexes of academic, behavioral, and socioemotional adjustment.