This research examines the intersection of competency-based education (CBE) and efficacy in schools, aiming to construct theories explaining how CBE contributes to teachers' beliefs in their ability to influence student achievement, foster collaboration, and strengthen collective efficacy. Employing a critical constructivist grounded theory approach, this study addresses the limited research on CBE's impact on teachers' efficacy beliefs, school culture, and collective efficacy. A critical constructivist grounded theory approach aligns with the study's aims of exploring the complex juncture of competency-based education, efficacy, and school culture. This approach focuses on participants' experiences and perspectives, acknowledging the role of power structures and social inequalities in shaping these experiences. The sample of 11 CBE-experienced teachers provided most of the data, and a focus group of five teachers with little working knowledge of CBE contributed to the collaborative development of emergent themes and theories. [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.]