Research over the past decade suggests teachers have low instructional self-efficacy/confidence and more concerns about implementing inclusive teaching practices. This quantitative correlational study explored whether reported concerns and demographic variables (gender, age, education, and years of teaching experience) predicts teachers' instructional self-efficacy with students with disabilities. The "Concerns about Inclusive Education" and the "Teachers' Efficacy in Implementing Inclusive Practices" scales were administered to 123 K-12 classroom teachers in Georgia. Data were subjected to hierarchical linear multiple regression to examine whether systematically adding select demographic variables and teachers' concern scores to the overall model significantly improved the model's ability to predict teachers' self-efficacy in implementing inclusive instruction. Analysis revealed a nonsignificant predictive relationship between all the demographic variables and self-efficacy, where these predictors accounted for only 2.9% of the variance with the criterion variable. A significant inverse relationship was found between the concern predictor and self-efficacy variables ([beta] = -0.414. t = -4.58, p < 0.001) with the concern variable accounting for an additional 15.80% of variance with self-efficacy, p = 0.009, R[superscript 2] = 0.216. Results suggest gender, age, educational qualification, and years of teaching experience contribute scant explanatory power to teachers' reported self-efficacy in implementing inclusive education. However, teachers' concerns about inclusive education offer some meaningful explanation about their instructional self-efficacy with students with disabilities. Future research studies need to replicate this study on a different sample population region, using quantitative, qualitative, or mixed research methods to understand better teachers' concerns and their PSE in implementing inclusive teaching practices to instruct students with disabilities. [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.]