Children and youth experiencing homelessness face unique challenges in accessing and succeeding in school. Subtitle VII-B of the McKinney-Vento Homeless Assistance Act, reauthorized in 2015 by Title IX, Part A of the Every Student Succeeds Act (42 U.S.C. § 11431 et seq.; hereafter the "McKinney-Vento Act"), establishes the definition of "homeless" used by U.S. public schools, and the educational rights to which children and youth experiencing homelessness are entitled. For schools to be able to provide services to students in homeless situations, they first must be able to identify these students. To this end, an effective understanding of the McKinney-Vento definition of "homeless" is a key first step to ensuring the delivery of needed supports to some of the nation's most vulnerable students. This brief provides local homeless education liaisons and other school personnel with an in-depth understanding of the McKinney-Vento definition of "homeless." The brief also outlines a step-by-step process for making determinations of McKinney-Vento eligibility on a case-by-case basis.