Housing First is a proven method of ending all types of homelessness and is the most effective approach to ending chronic homelessness. Housing First offers individuals and families experiencing homelessness immediate access to permanent affordable or supportive housing. Without clinical prerequisites like completion of a course of treatment or evidence of sobriety and with a low-threshold for entry, Housing First yields higher housing retention rates, lower returns to homelessness, and significant reductions in the use of crisis service and institutions. Due its high degree of success, Housing First is identified as a core strategy for ending homelessness in Opening Doors: the Federal Strategic Plan to End Homelessness and has become widely adopted by national and community-based organizations as a best practice for solving homelessness. Housing First permanent supportive housing models are typically designed for individuals or families who have complex service needs, who are often turned away from other affordable housing settings, and/or who are least likely to be able to proactively seek and obtain housing on their own. Housing First approaches also include rapid re-housing which provides quick access to permanent housing through interim rental assistance and supportive services on a time-limited basis. The approach has also evolved to encompass a community-level orientation to ending homelessness in which barriers to housing entry are removed and efforts are in place to prioritize the most vulnerable and high-need people for housing assistance. As Housing First approaches become adopted more widely, the need for clarity increases around what the Housing First approach entails and how to know whether a particular housing program or community approach is truly using a Housing First approach. Robust tools and instruments are available which can quantitatively assess and measure a housing program’s fidelity to Housing First, and recent research has attempted to rigorously evaluate Housing First implementation.2 For quick screening, policymakers and practitioners will benefit from this practical, easy to use guide to identify and assess the implementation of the core components of the Housing First approach.