Background. Although emerging Treatment as Prevention models can be effective in reducing HIV incidence among high-risk populations, many HIV infected individuals remain undiagnosed or fail to engage in HIV care. Methods. This study examined the factors associated with HIV testing and care among a population of substance using female sex workers. Results. Recent HIV testing was associated with higher education level, having a regular health care provider or clinic, recent crack use, and higher sexual risk behaviors; HIV treatment utilization was associated with higher levels of social support, having a regular health care provider or clinic, housing stability and insurance coverage. Qualitative data revealed HIV-related stigma, denial, social isolation, and substance use as barriers to HIV testing and treatment; social support and accessibility of services were key enablers. Conclusions. Improving HIV testing and linkage to treatment among female sex workers will require structural initiatives to reduce stigma and increase service seeking support.