Thesis advisor: Janet E. Helms / Historically, psychological theory and mental health researchers have viewed sex work as inherently harmful to sex workers and capable of producing negative mental and physical health effects (Sprankle et al., 2018). Moreover, research focused on clinicians’ expectations for sex workers in therapy has not specifically examined clinicians’ attitudes toward sex workers or sex work as separate concepts (Benoit et al., 2015; Koken, 2011; Ma et al., 2017). In addition, mental health professionals may not view sex work as legitimate work because of the virtual lack of evidence-based theoretical frameworks for guiding therapy for sex workers, and, therefore, may use prostitution stigma as a substitute for theory (Krumrei-Mancuso, 2017; Williamson & Cluse-Tolar, 2002). The present study investigated the extent to which mental health professionals’ expectations of sex work and sex workers were related to prostitution stigma and their perceptions of sex workers’ overall mental health and evaluations of sex work as decent work. In particular, the study investigated the extent to which mental health professionals stigmatized the work of sex workers. Mental health professionals (N = 201) read a clinical vignette and completed an online survey containing a demographic information sheet, the Attitudes Toward Prostitutes and Prostitution Scale (Levin & Peled, 2011); (c) the Decent Work Scale (Duffy et al., 2017), (d) the Hospital Anxiety and Depression Scale (Zigmond & Snaith, 1986), and (e) the PTSD-8 (Hansen et al., 2010). Results from multivariate multiple regression analyses supported that when mental health professionals held higher levels of stigma towards sex work and sex workers, they may diagnose the client with higher levels of PTSD symptoms. Further, the results supported that endorsement of a feminist orientation moderated the relationship between sex work stigma and diagnosis clients’ PTSD avoidance symptoms. The discussion included methodological limitations and implications for research and practice. / Thesis (PhD) — Boston College, 2020. / Submitted to: Boston College. Lynch School of Education. / Discipline: Counseling, Developmental and Educational Psychology.