In this quantitative and qualitative mixed study, the researcher focused on a range of factors that drive principals' decision making and examined the variables that affect principals' decision-making. The study assessed the extent to which principals' leadership and decision-making processes exert influence on the operations of inclusion classrooms including students with autism spectrum disorder at the elementary school level. The study examined the importance of having knowledge on instructional planning, evidence of effectiveness, specially designed instruction, collaborative decision-making, instructional strategies, governance, and technology. This study revealed that what the principals perceived in relation to the seven variables did not align with the practices in their various buildings. This means principals do not have the experience or training and rely heavily on consultants, specialists, and teachers to make decisions for the students on the autism spectrum in elementary inclusion classrooms. [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.]