Using cross-sectional analysis we examined residential status and associated differences in HIV risk behaviors among 3266 youth IDUs enrolled in an HIV prevention trial. a three-level outcome (homeless (37%), equivocally housed (17%), housed (46%)) was defined based in responses to two questions assessing subjective and objective criteria for homelessness were having lived in an out-of-home placement, been thrown out of the home or in juvenile detention, and experienced childhood abuse; while correlates included receiving home income from other and illegal sources, drinking alcohol or using methamphetamine at least daily, using shooting galleries, backloading and sex work. A subset of these variables were associated with being equivocally housed. HIV risk varies by housing status, with homeless IDUs at highest risk. Programs for IDUs should utilize a more specific definition of residential status to target IDUs needing intervention. (Authors)