Drop-in centers for homeless youth address basic needs for food, hygiene, and clothing, but can also provide critical services that address youth’s “higher-level” needs (e.g., substance use treatment, mental health care, HIV-related programs). Unlike other services that have restrictive rules, drop-in centers typically try to break down barriers and take a “come as you are” approach to engaging youth in services. Given their popularity, drop-in centers represent a promising location to deliver higher level services to youth that may not seek services elsewhere. A better understanding of the individual-level factors (e.g., characteristics of homeless youth) and agency-level factors (e.g., characteristics of staff and environment) that facilitate and impede youth engagement in drop-in centers will help inform research and outreach efforts designed to engage these at-risk youth in services. Thus, the goal of this review was to develop a preliminary conceptual model of drop-in center use by homeless youth. Towards this goal, we reviewed 20 available peer-reviewed papers and reports on the facilitators and barriers of drop-in center usage and consulted broader models of service utilization from both youth and adult studies to inform model development.