Organizational citizenship behavior (OCB) has been associated with organizational effectiveness in many studies. Therefore, it is important to learn more about how these behaviors can be improved in schools. Creating a reliable and valid measure of OCB that has conceptual equivalence across cultures is a first step in understanding and accumulating systematic knowledge of this construct. This study sought to validate in a Turkish school context a three-dimensional conceptualization and measurement of OCB created by Somech and Drach-Zahavy (2000). A confirmatory factor analysis of data from a sample of 710 school teachers supported the hypothesized factorial structure of the scales. In addition, 3 subscales correlated with an organizational commitment measure in the expected magnitude and direction, which provides evidence of the predictive validity of the scales. (Contains 4 tables and 1 figure.)