Problem. As inclusion becomes more of a mainstay in our educational system, educational leaders from all levels seek methods of training and retaining administrators to create successful outcomes for students in an inclusive environment. Purpose. The purpose of this quantitative correlational study was to examine the impact of principals' leadership self-efficacy on their attitude about special education inclusion, after controlling for (a) years of experience as a principal, (b) formal administration special education training, (c) extent of inclusion training, and (d) satisfaction level working with students with disabilities, within construct of social cognitive theory's triadic reciprocal causation model, in the San Diego County public schools as measured by the Principal and Inclusion Survey (PIS; Praisner, 2003) and the Principal Sense of Efficacy Scale (PSES; Tschannen-Moran & Gareis, 2004). This study also focused on understanding whether there was a significant difference in perception between elementary school (K--5/6) and middle/high school (6/7-12) principals' sense of self-efficacy and attitudes toward inclusion of students with disabilities. Methodology. This was a nonexperimental quantitative correlational study utilizing a multiple regression analysis to test the impact of principal leadership self-efficacy and attitude measures. Further, a t-test correlational analysis was performed to determine whether there is a significant difference in perception between elementary school (K-5/6) and middle/high school (6/7-12) principals' sense of self-efficacy and attitudes toward inclusionary of students with disabilities. PIS (Praisner, 2003) and PSES (Tschannen-Moran & Gareis, 2004), were administered via an online survey to school administrators in the San Diego County region to collect data about principals' demographic information, training and experience, attitude toward inclusion of students with special needs, and principal self-efficacy. Findings. The study revealed leadership self-efficacy did not statistically impact attitude about inclusion. Further, there was no significant difference in elementary and middle/high school principals' perception of leadership self-efficacy and their attitude about inclusion. Conclusions. Analysis of the independent variables revealed positive trends attributing to a positive attitude about inclusion. Principals predominantly described positive attitude about inclusion as well as high levels of leadership self-efficacy. Leaders with strong leadership self-efficacy require positive experiences working with students with disabilities. Heightening positive experience working with students with disabilities, and infusing special education training are recommended. Recommendations. District leaders should work collaboratively with principals when implementing special education programs by incorporating SCT based practices to increase positive interactions with students with disabilities to achieve 21st-century learning outcomes for all students in an inclusive environment. [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.]