Аннотация:This article is a theoretical and empirical analysis of the construct of collective teacher efficacy. First, a model of collective efficacy was elaborated for use in schools. Then, an operational measure of collective teacher efficacy was developed, tested, and found to have strong reliability and reasonable validity. Finally, using the instrument to examine urban elementary schools in one large midwestern district, collective teacher efficacy was positively associated with differences between schools in student-level achievement in both reading and mathematics.