This mixed-methods study reports on the perspectives of 208 teacher candidates on teaching children with developmental disabilities and delays (DD) in inclusive classrooms from Kindergarten to Grade 6. The questionnaire included items on demographics, experience, knowledge, and feelings of competence, advocacy, and sense of efficacy. Open-ended questions addressed challenges and successes experienced when including children with DD. Findings suggest that qualitative items elicited more positive responses than traditional questionnaire items and elicited more nuanced and sophisticated understanding of the challenges and successes associated with social inclusion. In the qualitative data, respondents showed understanding of dilemmas associated with inclusive education. Feelings of competence about teaching children with DD and about collaborating with colleagues predicted general sense of efficacy scores; those with experience advocating for individuals with disabilities reported greater knowledge, experience, and confidence related to teaching students with DD. Knowledge, experience, and confidence were highly correlated. Implications for teacher education are discussed.