The purpose of this study was to determine the impact of a professional development model on regular education middle school teachers' knowledge of best practices for teaching inclusive classes and attitudes toward teaching these classes. There were 19 regular education teachers who taught the core subjects. Findings for Research Question 1 showed teachers' knowledge of inclusive classrooms increased from pretest to posttest. Findings for Research Question 2 revealed teachers' perceptions on inclusive classrooms changed from preimplementation to postimplementation. Both increases had a large effect sizes. For Research Question 3, the most reoccurring theme was teachers do have a positive attitude towards teaching inclusive classes.