Although scholars have acknowledged the role of collaborative relationships of teachers in improving the quality of instruction, teacher collective efficacy continues to be a neglected construct in educational research. The purpose of this paper is to explore the relations between transformational school leadership, teacher self-efficacy and perceived collective teacher efficacy, using a sample of 120 permanent secondary-school teachers in Serbia, whose average age was 42.5. The results of the hierarchical regression analysis showed that transformational school leadership and teacher self-efficacy were independent predictors of teacher collective efficacy. The research findings also showed that individually-focused transformational leadership contributed significantly to an explanation of collective efficiency after controlling specific predictor effects of group-focused dimensions of transformational leadership. It is argued that the results have a double meaning. First, this study expanded the understanding of the relationship between different dimensions of transformational school leadership and collective teacher efficacy. Second, a contribution of teacher self-efficacy to collective efficacy beliefs was established, confirming the assumptions of social cognitive theory on reciprocal causality between two types of perceived efficacy: individual and collective.