We studied the prevalence of biologically confirmed HIV, Chlamydia, and Gonorrhea in a randomly selected sample of sheltered homeless women in New York City, and explored their association with demographic, homeless history, and clinical risk factors. 329 women were randomly selected from 28 family and single adult shelters. The estimated prevalence of HIV in the study sample is 0.6 % (±0.3 %); for Chlamydia it is 6.7 % (±2.2 %); for gonorrhea it is 0.9 % (±0.04 %). A history of childhood sexual abuse, arrest history, current psychotic symptoms, and substance use disorder placed women at greater risk of infection. We consider contextual factors that may yield under estimates of HIVprevalence in our sample and discuss how a more comprehensive prevalence estimate might be constructed. Findings underscore the importance of offering HIV/STI testing, counseling, and HIV risk prevention interventions to homeless women and suggest that interventions should be tailored to the needs of specific subgroups of homeless women (Authors).