The existing body of scholarly knowledge has little research focused specifically on formal, non-formal, and informal education and training's contribution to the development of expert capabilities. The purpose of this research was to find out how experts in their field of study or work perceived education and training learning contexts contributed to the development of their capabilities. The theoretical foundation for the study was the self-regulation theory. A qualitative case study methodology was used to explore the problem with 10 individuals from different geographic areas that have recognized expertise in their field of study or work. The research questions asked participants to explain how formal, non-formal, and informal education and training contributed to the development of their capabilities. NVivo 11, qualitative data analysis software, was used analyze the participants' attributions to learning contexts. The results of the study show all of the learning contexts contributed to the development of the experts' capabilities; however, formal training's developmental contributions were clearly the major contributor for all of the participants. Non-formal training was usually the second largest contributor of the three. While informal training generally underperformed both, informal learning context's attributions exceeded non-formal in four situations. The results provide organizations and individuals with new knowledge on how formal, non-formal, and informal education and training contexts can be utilized to accomplish developmental goals effectively. [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.]