This study examines changes in attitudes, teaching efficacy, and concerns about inclusive education in a sample of 2361 teachers in Hong Kong who took a professional learning course about inclusive education. Participants completed a questionnaire seeking demographic information and their perceptions about these three aspects of inclusive education both before and after their course. Items were selected from the Sentiments, Attitudes, and Concerns about Inclusive Education Scale Revised and Teacher Efficacy for Inclusive Practices scales that were of relevance to the objectives of this study. The results indicate that in all three areas of acceptance, teaching efficacy, and concerns about inclusive education, positive improvements were made as a result of training, although generally this improvement was strongest in areas that teachers felt were under their direct control. The small amount of change in areas that teachers felt were not under their control may indicate that whatever change initiatives are put in place, they need to be holistic and systemic.