Professionalization of the human service nonprofit (HSNP) sector has been well documented. While professionalization of the human services can result in improved client outcomes, it may also lead to a reduction of political participation of these organizations. For “underground” service providers, organizations providing unsanctioned services to populations engaged in illicit behavior, professionalization accompanies the transition of organizations to sanctioned service providers. Using qualitative methodology, this paper explores the professionalization of an underground service organization for sex workers. I argue that professionalization, while not a panacea, may increase underground organizations’ ability to engage in politics by establishing credibility within their institutional environment.