The need to understand the differences in the self-efficacy of K-12 mathematics teachers based on teachers' characteristics and school factors is imperative because research has shown teachers' self-efficacy to be a mediating factor on students' academic achievement. As such, education policymakers and school administrators need to understand variances in teachers' self-efficacy so that they could better implement programs to enhance and support the self-efficacy of teachers. This quantitative research used an exploratory cross-sectional design. The study consisted of 50 K-12 in-service teachers from two rural districts in a southeastern state in the United States. The study examined differences in teachers' sense of self-efficacy (TSES) for teaching mathematics at the K-12 level based on teachers' gender, teaching experience, education level, and school type (elementary school, middle school, and high school). Findings suggest that teachers' overall sense of self-efficacy and subscales efficacies (student engagement, instructional strategies, and classroom management) based on school factors and demographic variables were comparable in the context of rural teachers in the southeast United States. The findings of insignificant differences in teachers' sense of self-efficacy that were discovered in this research might be due to the positive working environment among staff and the dual role of principals as teachers and school leaders that are characteristic of schools in rural settings. Based on the findings of this research, future studies might want to examine the influence of suburban and urban environments on teachers' sense of efficacy for teaching mathematics in K-12 settings, for the experiences of teachers in rural settings might be unique when compared to teachers in other school environments. [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.]