Organizational routines are viewed as a source of strategic competitive advantage that enhances firm performance. How do organizations continue to adhere to organizational routines after the routines are integrated in the work flow? I introduce and define a new construct, adherence to routines, which captures the theoretical phenomenon of maintaining the repeatability of organizational routines. I apply trait activation theory to explain why employees adhere to routines. I theorize that three individual traits: (1) conscientiousness, (2) openness to experience, and (3) individual entrepreneurial orientation impact adherence to routines. Moreover, I theorize that employees' perception of their supervisors' initiating structure leadership moderates the relationships between the three individual traits and adherence to routines. In this study, I developed a scale for the newly introduced construct adherence to routines. Using a sample of 543 employees surveyed in the U.S., I validated the new scale. The findings also support my arguments that conscientiousness is positively related to adherence to routines, and that openness to experience and individual entrepreneurial orientation are negatively related to adherence to routines. I also found support for employees' perception of their supervisors' initiating structure leadership as a moderator to the relationship between conscientiousness and adherence to routines. These results suggest that initiating structure leadership may have triggered the expression of conscientiousness, resulting in higher levels of adherence to routines.