Homeless youth are a population at a high risk for suicidal behavior. A previous exploratory study emphasized the importance of feeling trapped or helpless, which appeared to mediate the impact of other risk variables. Confirmatory work was needed to test this inductively derived model. Two hundred eight homeless youths completed surveys on the streets and in agencies in New York City and Toronto. Structural equation modeling was used to test a theoretical model developed from exploratory work, and regression analyses were used to examine the influence of home and street contextual variables. The centrality of the trapped experience in a model incorporating drug use and dependence, abusive family history, loneliness, low self-esteem, and suicidality was confirmed. Other findings included a marked reduction in reported suicidal behavior following participants' leaving home, with family violence, being thrown out of the home, neglect, poor physical health, and having suicidal friends showing strong relationships with suicidality. (Contains 1 figure and 2 tables.)