Homelessness has become an all-too pervasive and visible problem in Canada. It has spread from large urban centres to rural, northern and remote communities. While a number of programs have been developed to address the needs of the homeless in the hope of re-housing them, a large population of those at risk of homelessness receive little attention until their needs become dire. There are both societal and individual costs to be borne when this occurs. Preventing homelessness has the potential to save countless individuals from the misery of life on the streets. However, with the major effort focusing on assisting those that become homeless, where does one start to prevent this significant social ill? The few authors who have written about prevention provide no clear answers, but raise the importance of prevention as a focus (Burt, Pearson & Montgomery, 2007, US; Moses, Kresky-Wolf, Bassuk & Broundstein, 2007, US; Wireman, 2007, US). One key question is how to define the population of those at risk of becoming homeless. The research team originally conducted a literature review summarizing research, particularly published studies from the past decade or so, that focus on the risk factors, predictors and pathways in and out of homelessness (Tutty et al., 2009). Unpublished research reports from reputable organization, especially Canadian ones, were also included. Our primary focus was on factors that differentiate those that have become absolutely homeless from those that are on the cusp of homelessness, either being relatively homeless, or living in hidden homelessness. As such, the analysis focused particularly on studies that differentiated between these groups. We also searched for articles on resilience and protective factors, again finding relatively few. These assets and protective factors formed the core of a screening tool, The Homelessness Assets and Risk Screening Tool (HART) that could be used to identify vulnerability to homelessness in at-risk populations, but those not yet experiencing homelessness, in the hope of providing early interventions. The purpose of the current research is to test the validity of the HART, including its predictive validity with respect to identifying those at risk of homelessness. A second objective was to determine the applicability of the HART tool in a Calgary context and assess the tool’s feasibility from an administrative perspective. This was achieved by utilizing the HART tool with an initial sample of service recipients at multiple community agencies within the city of Calgary. This allowed us to test the tool’s content validity (the ability to capture elements of risk) by comparing responses to the HART to responses to the ETHOS (described below) and to test the HART’s predictive validity (ability to predict homelessness) by tracking a sub-sample of participants over a one-year period.