Although street-involved youth contend with many health and social problems, the extent to which vulnerable youth engage with supportive services has not been well described. This study sought to examine the prevalence and correlates associated with having difficulty accessing health and social services among a prospective cohort of street-involved youth in Vancouver, Canada. Among 1019 street-involved youth, 650 (64%) reported having difficulty accessing services during the study period. In a multivariate analysis, youth who reported having difficulty accessing services were significantly more likely to be socially and economically vulnerable. Specifically, they were more likely to report severe housing instability, high-intensity drug use, recent interactions with law enforcement, drug dealing, and histories of violence and physical abuse. Study findings point to opportunities to improve access to services among vulnerable youth through removal of blanket age restrictions for youth services, establishing youth-centric social housing, and supporting peer-driven, low-threshold services.