The present study examines the role of transformational leadership as one of the antecedents of organizational citizenship behaviors (OCB). The extant literature that examines antecedents of OCB, many times, focuses on the direct effects of a variety of variables, ignoring the processes through which such variables encourage OCB. Thereby the OCB literature is full of black box theories. The current study attempts to address this black box by identifying and examining organizational identification as the process through which transformational leaders bring about OCB from their employees. Hence, the major contribution of this study is investigating the mediating role of organizational identification in transformational leadership-OCB association. Drawing from the theoretical framework of Social Identity Approach, three hypotheses were proposed. The hypotheses were tested using a survey in a sample of 148 bank employees using mediated regression analysis. All study hypotheses were supported. Implication and limitations of the study are discussed