This chapter focused on the effectiveness of a professional development initiative on the planning, designing, and implementing project-based learning in mathematics, science, and special education classrooms. The purpose was to highlight project-based learning and the development of a professional development learning community that provided unique ways in which teachers engaged with a variety of learning tasks, assessments, and resources while practicing vital mathematics and science skills with diverse students. Attention was given to the importance of teacher attitude and confidence, collaboration, school support, barriers, and increasing student engagement. The case study method was used to amass and probe data. The results indicated valuable suggestions about the effectiveness of professional development for active engagement in project-based learning through networking, differentiating instructional strategies, creating new assessment tools, and gaining content knowledge and pedagogical skills.