Evidence suggests preschool age students with disabilities (SWD) benefit from inclusive settings. Inclusive education has positive impacts on students' social-emotional, language, and cognitive skills. Yet, preschool age SWD continue to have limited access to inclusive education, and research suggests numerous reasons, including teacher practice. The setting of this study, a K-12 school district in Southern California, had not met expectations related to the percentage of children participating in inclusive settings and the percentage of children demonstrating improved developmental growth. Relevant literature suggests that teacher attitudes and beliefs are the most frequently reported barriers to inclusion of preschool age SWD. To this end, this study examined the differences between early childhood education and early childhood special education teachers' attitudes and beliefs and student growth outcomes across the special education program continuum, and it investigated whether teachers' attitudes and beliefs about inclusion impact the social-emotional, language, and cognitive outcomes of their students. For this study, 39 teachers completed a survey that investigated their attitudes and beliefs related to social-emotional benefits, academic benefits, outcomes of inclusive practices, and implementation of inclusion. In addition to teacher surveys, student assessment data (using the Desired Results Developmental Profile, 2015) of 182 students were analyzed to determine student growth in one year. Mean comparisons and multilevel modeling were used to determine if teacher attitudes and beliefs influenced student assessment outcomes. The analysis revealed that early childhood special education teachers had more positive attitudes toward the social-emotional benefits of inclusion of SWD than did early childhood education teachers. They also had more positive attitudes toward the implementation of inclusive practices. SWD participating in coteaching, inclusive models demonstrated higher social-emotional, literacy and language, and cognitive development growth outcomes than SWD participating in self-contained models. There was a correlation between teachers' attitudes and beliefs related to the social-emotional benefits and academic benefits of inclusion. Student participation in inclusion was a marginally significant predictor of higher social-emotional growth, and inclusion of students with speech and language impairments was a marginally significant predictor of higher cognitive growth. [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.]