The new 21st century global economy favors highly skilled, highly educated workers. School districts across the country are looking for ways to teach and assess competencies as outlined in the 21st century framework (Wagner, 2014). Forward thinking school districts are choosing to implement the effective instructional approach of project-based learning (PBL) to address the needs for U.S. students to be globally competitive. Changing teacher-centered classrooms to students driving their own education has translated into a major overhaul in how professional development is administered (Almulla, 2020). The purpose of this study is to explore best practice in teacher training for implementation and ongoing support for project-based learning instruction and 21st century competencies in three Midwest CAPS school districts. Constructivist learning theory and experiential learning theory were used to frame the study. Research questions were created to gather perceptions based on best practice of PBL professional development to support instructional methods and 21st century skills and its role in increasing student achievement. The research questions focused on gathering perceptual data on supporting and implementing PBL, student achievement, and barriers to effective PBL teacher training. This qualitative study used surveys and focus-group interviews to gather perceptions of CAPS instructors. Data and discussion of the findings would benefit districts seeking to develop or strengthen CAPS instructors' professional development to support student learning. Participants uncovered that CAPS programs were either lacking in PBL teacher training or the professional development being offered was inadequate. Participants expressed frustration and confusion in their PBL teacher training and preferred a mentor over a coach for instructional support. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]