The study has designed a model for assessing student leadership competencies development and affecting factors in university. It is based on the findings in Fars province- Iran. 400 college students were randomly selected from 26 institutions. The study used qualitative (Focus group, individual in-depth interview and library) and quantitative (path analysis) methods. Numerous studies have been carried out examining the effect of involvement and environment variables, leadership attitude and leadership behavior on the student leadership competencies development. However, there is little research conducted on the effect of leadership attitude and leadership behavior such as mediatory variable on the student leadership competencies development. The model suggests that systematic thinking, challenging the process, inspiring a shared vision, enabling others to act, modeling the way and encouraging the heart are considered important in student leadership competencies development. The authors propose that student affair practitioners need to rethink some of the key assumptions of their student leadership and practices in order to meet the needs of a changing student body. Also, college and universities need to be cognizant of these differences, as they develop leadership programs, training opportunities, leadership course and co- curricular and extracurricular activities.