The purpose of this study was to examine the effect of professional development instruction on teacher perceptions of competence when including students with special needs in music classrooms. Subjects for the study were in-service music educators (N = 43) enrolled in an online graduate-level course specifically created to address the skills and knowledge needed to effectively include students with special needs in classroom activities. The researchers conducted this inquiry using the one-group pretest-posttest design. A paired-samples t test revealed that a -5.6 difference between pretest and posttest means was significant (p less than 0.05). Comments were also solicited from the participants to further explain the effect of instruction. Areas in which participants expressed the most growth were related to transparency, knowing both students' rights and teachers' obligations, and modifying teaching strategies and the learning environment. (Contains 3 tables.)