The concept of leadership is recognized in areas including the business world, education systems, and religious organizations; however, it has a different meaning depending on the context in which is used. The purpose of this study was to examine the association between the perceived personal characteristics of building principals and the impact they had on the level of collective efficacy established among members of their building leadership teams. Members of building leadership teams in five large, public high schools shared their perceptions of the level of efficacy established among team members, while also identifying the perceived personal characteristics of the building principal that worked most directly with the teams. The data collected from the two survey instruments administered was analyzed utilizing a descriptive, correlational method to determine the personal characteristics building principal demonstrated that had the greatest and least impact on the collective efficacy established among team members. The researcher found the characteristics of friendly and self-confident had the greatest, positive impact on collective efficacy, and the characteristic of passionate had the greatest, negative impact on collective efficacy. The information gathered from this research aimed to inform building principals about the impact they had on the teams they worked with, which is critical in helping teams reach their greatest collective capacity and ultimately impact student achievement. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]