Indiana University-Purdue University Indianapolis (IUPUI) / The Saudi Arabian government launched Vision 2030 in 2016 that will have repercussions for all aspects of society. The Saudi nonprofit sector has undergone massive and unprecedented reform ever since. Professionalism is a major tool for this reform, prompting an increasing need for research on the topic of organizational professionalism. This dissertation examines how to define and measure organizational professionalism and its implications in the Saudi nonprofit sector. After introducing key concepts and historical context in Chapter 1, I include three articles that address these themes. Using grounded theory methodology, in Chapter 2, I focus on how nonprofit workers in Saudi Arabia define professionalism. In Chapter 3, I develop, test, and validate a professionalism scale from Saudi nonprofit workers’ perspective. In Chapter 4, I examine implications of professionalism on Saudi nonprofit employees’ work-related wellbeing: job satisfaction, turnover intention, and job burnout. In the Conclusion (Chapter 5), I discuss results along with potential implications for policies and practice, recommendations, limitations, and directions for future research.