This study investigated HIV risk among homeless and formerly homeless young adults by examining risky sex behaviors (e.g., condomless sex, exchange sex, and sex with multiple persons) using 90-day and daily recall methods. Data came from a sample of young adults (aged 18-27) with current (n = 101) or past (n = 109) homelessness experience in Los Angeles, California, recruited between 2017 and 2019. Baseline surveys queried demographics and sexual history. Daily retrospective surveys queried sexual events. Multiple logistic regressions were used to test the effects of demographic characteristics including homelessness history, relationship status, substance use, and sexual history on risky sex outcomes. In this sample, 26% reported never using a condom during anal or vaginal sex in the past 90 days, 5% reported testing positive for HIV, 82% had limited to no knowledge of preexposure prophylaxis, and 8% reported having had exchange sex during a 7-day measurement period, with those experiencing homelessness more likely to report. The study suggests supportive housing can reduce the occurrence of exchange sex but that HIV prevention services are still needed in homeless and housing programs to promote safe sexual practices.