Sex work stigma can negatively impact health care utilization by sex workers, including utilization of services for HIV prevention and treatment. It is important to measure and address sex work stigma to improve access and retention in HIV and other health services, yet a gap remains in the literature on sex work stigma. This may in part be due to lack of validated sex work stigma measurement instruments. We developed a set of 26 items on experienced stigma, identified from extant research, encompassing various components and sources of sex work stigma (stigma from family, community, health care workers, and police). We then tested items in a population of 729 male and female sex workers in Kenya, recruited from health facilities in 4 sites-Nairobi, Busia, Homabay, and Kitui. Confirmatory factor analysis was used to test and establish a conceptually and statistically valid scale for measuring experienced sex work stigma. The confirmatory factor analysis supported a 4-factor experienced Stigma Scale ( 2 p Ͻ .001; root mean square error of approximation ϭ 0.06; comparative fit index ϭ 0.93; and standardized root-mean-square residual ϭ 0.05). The final 19-item scale included 4 subscales: health care worker stigma (7 items), community-level stigma (3 items), family-level stigma (4 items), and police/law enforcement-related stigma (5 items); the Sex Work Experienced Stigma Scale demonstrated good convergent, discriminant, and known-group validity as well as excellent internal consistency (Cronbach's alpha ϭ .93). Given the demonstrated This article was published Online First November 11, 2019.