This paper includes results from a study that examined the relationships between teacher discipline, type of teaching degree, and teacher feelings of preparedness and the self-efficacy beliefs (competence and confidence) of early intervention and preschool teachers with regard to either natural environment or inclusion practices. The participants were 1,178 educators employed in either Part C early intervention (n = 615) or Part B (619) preschool special education (n = 563) programs in 45 United States, the District of Columbia, and the U.S. Virgin Islands. Results showed that feelings of preservice teacher preparedness were related to the self-efficacy beliefs of both early intervention and preschool special education teachers, and that teacher discipline and the type of degree moderated the relationship between teacher preparedness and self-efficacy beliefs among preschool special education but not early intervention teachers. Implications for understanding preservice factors contributing to teacher adoption and use of natural environment or inclusion practices are described.