Studies of principals' leadership behavior have been limited to purely descriptive content with no insight into the meanings they ascribe to their actions. The inclusion of individual interpretation is crucial to understanding the link between actions and their intended impact on a situation. The methodology used in this study assesses principals' own interpretation of their behavior at the time of an action. An "Instructional Leadership Inventory" consisting of 48 items designed to measure the "Five Dimensions of Instructional Leadership" (defines mission, manages curriculum, supervises teaching, monitors student progress, and promotes instructional climate) was given to each of the 81 principals representing schools from the Chicago metropolitan area studied along with a beeper. Five times each day during a regular work week, principals were signaled at random to fill out a behavioral assessment form. Results of the survey relate the dimensions of instructional leadership to behavioral reports made by the principals. The most dramatic finding is the absence of consistent differences in the types of activities that effective vs. less effective principals engage in. Distinctions lie in specific meanings leaders ascribe to what they did. A comprehensive listing of explanations and results is included. (EJS)