The purpose of this study was to explore the attitudes, practices, and behaviors of principals who foster teacher collective efficacy. The research questions were developed based upon Bandura's social cognitive theory to include (a) what are the "attitudes" held by principals that influence TCE; (b) what are the "behaviors" enacted by principals that influence TCE; (c) what are the "practices" employed by principals that influence TCE. The study utilized a qualitative approach with a multisite case study design. The Collective Teacher Efficacy Scale developed by Goddard et al. was used to measure TCE of participating schools. The survey results were analyzed to facilitate the selection of four cases. Data were gathered through semistructured interviews from the principal and three to five teachers at each school. The data from each interview were developed through content analysis and then examined in relation to all other interviews in a cross-case analysis. The results presented fundamental attitudes, behaviors, and practices principals used in fostering collective efficacy. Principals held attitudes that student success was a top priority, as well as attitudes of responsibility, caring, shared purpose, confidence, and collaboration. Principal behaviors included supporting teachers, communicating, knowing teachers, and modeling desired behaviors. Principal practices included establishing an environment of openness and support, establishing shared expectations, facilitating teacher voice, providing opportunities to collaborate, and promoting continuous learning. [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/en-US/products/dissertations/individuals.shtml.]