With the changes in accreditation requirements, engineering programs are deciding how to best teach and assess leadership skills among their students. One frequently utilized method of assessment is giving students a pre-and post-test. The goal of this study is to explore the use of a pre-, mid-, and post-assessment model to assess leadership behaviors among mechanical engineering students in a capstone design course. A quantitative approach was taken, using an adapted Managerial Behavior Instrument, which follows the tenets of the Competing Values Framework (CVF). The CVF highlights that the most effective leaders have skills in all four leadership orientations: Collaborate, Create, Control, and Compete. Those who excel in all areas are shown to have behavioral complexity, which equates to the ability to enact leadership actions that align with the needs of a given context and situation. Mechanical engineering students were given the same survey near the beginning of the year-long course, at just past the mid-point of the course, and in the last week of the course. Data were analyzed for the full sample, by comparing scores for men and women, and by comparing trends of students who started the course with high complexity ratings to those who started the course with low complexity ratings. Results show significant changes from the pre-to post-assessments in the Create, Control, and Compete quadrants. Men, as a group, showed similar trends to the larger sample, while women significantly increased their scores only in Create from pre-to post-assessment. Men and women showed similar change from pre-to post-assessments. Students who rated themselves as behaviorally complex at the beginning of the semester had lower scores at the end of the semester. Students who rated themselves as having low complexity at the beginning of the semester steadily raised their scores on the mid-and post-assessments. These findings are informative to engineering educators who are exploring ways to add leadership development into their curriculum by providing insights on student leadership scores and an example of one assessment method of leadership behaviors. The results implicate intensive team-based courses such as capstone design as being one part of a typical engineering curriculum that contributes to leadership development.