Highly effective management, particularly in a role of team leader, is a crucial importance to the success of any school. To be highly effective as team leaders school principals need to know something about their selves. Several models exist that help managers to understand their development. Among these models Self-development is an approach that emphasizes the importance of lifelong learning. It differs from traditional, instructor-centered approaches by giving the primary responsibility for learning to learners themselves: They are shown how to use a variety of methods to diagnose their needs and then create an action plan for implementing change. In effect, self-development is about change of self by self. The aims of this research were to identify and rank need to 11 attributes from a sample of 151 Iranian school principals view which were found to be possessed by the successful managers. These qualities fall into three groups, which constitute three different levels. A 110 item format questionnaire was the main instrument for data collection. Responses to the items were made on a five-point Likert scale anchored with strongly agree and strongly disagree and coefficient alphas of measurer was in a satisfactory level (.94). The overall conclusions of the study showed that there were statistically significant differences in principals needs level based on theirs demographic variables. Regarding 3 levels of qualities, different mean ranks were obtained. Mean ranks for level of "Skill and attributes" was 2.36 and was in the first priority from the principal view. Also, among 11 managerial qualities the most principals expressed high need to develop their "mental agility" attribute. Female principal declared more needs for developing their "analytic and problem solving skills" than males one.
