The main purpose of this longitudinal study was to conceptualize the self-efficacy of aspiring principals as a dynamic concept. This study aimed to explore the structure and relations between the components of self-efficacy and to determine the nature and direction of change in the perceived self-efficacy of aspiring principals following a 2-year training program. The study was based on Facet Theory (Gutman, Psychmetrika 33:469-506, 1968), but also included some traditional statistics. The present study was carried out in two stages during 2005-2007. One-hundred and fifty aspiring principals from five academic colleges and universities in Israel who participated in a 2-year training program completed the same self-efficacy questionnaire during the first month of the program (October 2005-stage 1 and during the last month of the program (May 2007-stage 2). The nature as well as the direction of the aspiring principals' perceived self-efficacy changed following the 2-year training program. The perception of the nature of the principal's role remained unchanged.