This study focused on the relationship between the principal's sense of self efficacy and the faculty's sense of collective efficacy in independent schools in the metropolitan area of Washington, D.C. Principals and teachers from sixteen private schools participated by completing surveys on efficacy. Principals completed the Principal Self-Efficacy Scale (PSES) developed by Tschannen-Moran and Gareis (2004) and demographic questions about the school and the principal. Teachers completed the Collective Efficacy Scale-Short Form (CE-Short Form) developed by Goddard (2002) and two demographic questions on their gender and years at the current school. The dependent variables were the collective efficacy scores (Total Collective Efficacy, Group Competence, and Task Analysis) and the independent variables were the principal efficacy scores (Total Principal Efficacy, Efficacy for Management, Efficacy for Instructional Leadership, and Efficacy for Moral Leadership). Control variables of school size, teacher gender, principal gender, and number of years as principal at the current school were added in to the hierarchical stepwise regression analysis, Descriptive/correlational statistics showed mixed results. To answer the research questions about the extent to which principal efficacy and related constructs explain the variance in collective efficacy and related constructs over and above the control variables, hierarchical stepwise regressions were run using SPSS/PASW version 18. All of the variables explained 9% of the variability in Group Competence scores, 27% of the variability in Task Analysis scores, and 21% of the variability in Collective Efficacy scores. Efficacy for Instructional Leadership explained 2% of the variability in Group Competence, Total Principal Efficacy explained 2% of the variability in Task Analysis, and none of the Principal Efficacy constructs explained any of the variability in Collective Efficacy. The size of the school and teacher gender accounted for most of the variability in teacher efficacy. Teachers in smaller schools and female teachers ranked their schools higher in each construct of collective efficacy. Recommendations for future research in this important and understudied topic of principal efficacy are included. [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://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]