We develop a theoretical model of city manager professionalism addressing professional guidance and commitment, and four public service values: ethical solutions, neutral competence, political responsiveness, and political solutions. We tested these professionalism values on a national survey sample of city managers in the United States. Using structural equation modeling, we found evidence that professionalism acted directly on reported ethical behavior, and ethical behavior indirectly explained political responsiveness positively and political solutions negatively through neutral competence. Our analysis supports arguments that public service professionalization is possible and clarifies the pathways toward this important goal. Our study focuses on understanding how involvement in professional associations and activities relates to city manager perceptions of their own values and competence.