The aims of the study were to (a) examine the factor structure of measures of teachers' collective efficacy (TCE), job stress, and job satisfaction, and (b) explore the mediating effect of collective efficacy on the relationship between job stress and job satisfaction. The sample consisted of 951 teachers from elementary and secondary schools in Canada. Measures of TCE, job stress, and job satisfaction showed consistent factor patterns across school levels and gender. Female teachers reported significantly higher levels of stress from workload and student misbehavior. TCE for student discipline mediated the influence of job stress from student misbehavior on job satisfaction, and the relationship was consistent across groups. The results from this study suggest that teachers' collective efficacy may lower teachers' stress attributed to student behavior. (Contains 3 tables and 1 figure.)