This paper by Eric Macnaughton, Geoffrey Nelson, Paula Goering,and Myra Piat presents a study that aimed to understand the sustainability of the At Home/Chez Soi (AHCS) project with respect to its wider impact on homelessness policy in Canada and internationally. Using a qualitative case study approach with 15 key informant interviews (with project leaders and decision-makers) and archival data, the researchers examined the strategies adopted to achieve sustainability of the Housing First (HF) programs implemented during this demonstration project. The main focus was on the impacts that these strategies had on national policy. The study reveals four main themes: (1) the importance of evidence that was both rigorous and contextually relevant; (2) the value of framing the evidence in a way to achieve maximum impact in the decision-making context; (3) the importance of strong researcher-decisionmaker relationships, which evolved through an integrated knowledge translation approach; and (4) the value of resources and expertise provided by key stakeholders. A subsidiary theme was the importance of timing.