Transformational leadership researchers have given little attention to teacher expectations that mediate between goals and actions. The most important of these expectations, teacher efficacy, refers to teacher beliefs that they will be able to bring about student learning. This study examined the mediating effects of teacher efficacy by comparing two models derived from Bandura's social-cognitive theory. Model A hypothesized that transformational leadership would contribute to teacher commitment to organizational values exclusively through collective teacher efficacy. Model B hypothesized that leadership would have direct effects on teacher commitment and indirect effects through teacher efficacy. Data from 3,074 teachers in 218 elementary schools in a cross-validation sample design provided greater support for Model B than Model A. Transformational leadership had an impact on the collective teacher efficacy of the school; teacher efficacy alone predicted teacher commitment to community partnerships; and transformational leadership had direct and indirect effects on teacher commitment to school mission and commitment to professional learning community. (Contains 4 figures, 5 tables, and 1 note.)