The prevalence rate of autism spectrum disorder (ASD) among school aged children in the US has increased exponentially, compared to estimates from the year 2000. Increased numbers of elementary students with ASD are spending 80% or more of the school day in general education settings, which may pose challenges for both veteran and beginning elementary teachers. Furthermore, there are more rigorous mathematics and science standards that beginning teachers will be responsible for providing instruction to all students, including those with ASD. The transition of mathematics and science standards impacts both elementary teachers and special education teachers because many professional teaching organizations feel both types of instructors should have the proper knowledge in these subject areas for effective instruction. However, there is evidence that both special education and elementary education teachers may not feel efficacious to teach this content. Established and novel survey instruments were administered to a sample of 39 senior pre-service teachers majoring in special education and elementary education, to obtain data related to their field teaching experiences, personal experience interacting with individuals with ASD, and their reported undergraduate coursework. This study was designed to investigate and compare the self-efficacy beliefs of pre-service teachers majoring in special education and elementary education, which was focused on the following context-specific instructional situations: 1) mathematics instruction; 2) science instruction; 3) mathematics instruction to students with ASD; 4) science instruction to students with ASD; and 5) general instructional considerations for teaching students with ASD. Results of the study indicated elementary education pre-service teachers had lower teaching efficacy beliefs in teaching mathematics and science to students with ASD, compared to their mean teaching efficacy scores for the instruction with mathematics and science in general situations. Furthermore, elementary education majors scored significantly lower on teaching mathematics to students with ASD, teaching science to students with ASD, and teaching students with ASD in general, compared to their special education peers in the obtained sample. The new instruments measuring mathematics and science teaching efficacy were determined to have good reliability. Implications for teacher preparation programs and recommendations for future research are discussed. [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.]