This book is a collection of peer-reviewed research for service providers on best and promising mental health practices for street-involved youth. It contains four sections covering a range of topics that service providers inquire about most often. Part 1: Approaches and Interventions describes specific approaches for addressing mental health and substance use challenges of youth experiencing homelessness. Part 2: Specific Groups reflects the diversity among youth experiencing homelessness. While many interventions and approaches may be relevant across groups, attention should be paid to the unique needs to LGBTQ, Native, newcomer, and other youth populations. Part 3: Contexts and Considerations focuses on where and how interventions are delivered, including drop-in centers and outreach. Part 4: Assessment and Evaluation aims to support service providers who are increasingly required to provide outcome evidence in order to obtain funding and inform service improvement and resource allocation.