This observational study explored the connections between collaborative teacher learning communities as related to teacher efficacy in the largest high schools in Ohio. These communities are typically called Small Learning Communities and Professional Learning Communities. Small Learning Communities are usually created with academic content area ninth or tenth grade teachers, involve sharing a group of students across the school day, have common planning time to create similar expectations, and are provided professional development in order to more effectively collaborate on student achievement. Professional Learning Communities allow groups of teachers to evaluate student work, and achievement data trends, but do not involve purposeful scheduling to share students across the school day. Each of these models was examined for teacher efficacy. Investigating such connections is key, because teacher efficacy has been linked to student achievement. Findings demonstrated that participation in collaborative learning communities, specifically small learning communities and professional learning communities appear to be linked to high school teachers' sense of self-efficacy. The supportive structures of common planning time, professional development and professional learning communities did show statistically significant relationships to teacher efficacy in this study. High school teachers showed higher levels of efficacious beliefs in the subset areas of instruction and student engagement, and lowest efficacy scores in the subset of classroom management on the TSES instrument, when engaged in collaborative learning communities, as compared to teachers who were not participating in such structures. The dependent variable, teachers' sense of self-efficacy, was measured using the twelve question short form of the Teachers' Sense of Self-efficacy Scale (TSES) (Tschannen-Moran & Woolfolk Hoy, 2001) that contains questions related to student instruction, student engagement and classroom management. The independent variables were enrollment in small learning communities, common planning time, professional development and professional learning community. Auxiliary analysis included school demographics of student achievement, as measured by the Reading Ohio Graduation Test, student attendance, student discipline rates, student socioeconomic status and graduation rates. [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.]