This paper summarizes a stream of research aimed at developing and validating a measure of employee commitment to work organizations. The instrument, developed by Porter and his colleagues, is called the Organizational Commitment Questionnaire (OCQ). Based on a series of studies among 2563 employees in nine divergent organizations, satisfactory test-retest reliabilities and internal consistency reliabilities were found. In addition, cross-validated evidence of acceptable levels of predictive, convergent, and discriminant validity emerged for the instrument. Norms for males and females are presented based on the available sample. Possible instrument limitations and future research needs on the measurement and study of organizational commitment are reviewed.