jats:secjats:titleObjective</jats:title>jats:pThe objective of this study was to identify and understand the health system contexts and mechanisms that allow for homeless populations to access appropriate healthcare when needed.</jats:p></jats:sec>jats:secjats:titleDesign</jats:title>jats:pA realist review.</jats:p></jats:sec>jats:secjats:titleData sources</jats:title>jats:pOvid MEDLINE, embase.com, CINAHL, ASSIA and grey literature until April 2019.</jats:p></jats:sec>jats:secjats:titleEligibility criteria for selecting studies</jats:title>jats:pThe purpose of the review was to identify health system patterns which enable access to healthcare for people who experience homelessness. Peer-reviewed articles were identified through a systematic search, grey literature search, citation tracking and expert recommendations. Studies meeting the inclusion criteria were assessed for rigour and relevance and coded to identify data relating to contexts, mechanisms and/or outcomes.</jats:p></jats:sec>jats:secjats:titleAnalysis</jats:title>jats:pInductive and deductive coding was used to generate context–mechanism–outcome configurations, which were refined and then used to build several iterations of the overarching programme theory.</jats:p></jats:sec>jats:secjats:titleResults</jats:title>jats:pSystematic searching identified 330 review articles, of which 24 were included. An additional 11 grey literature and primary sources were identified through citation tracking and expert recommendation. Additional purposive searching of grey literature yielded 50 records, of which 12 were included, for a total of 47 included sources. The analysis found that healthcare access for populations experiencing homelessness is improved when services are coordinated and delivered in a way that is organised around the person with a high degree of flexibility and a culture that rejects stigma, generating trusting relationships between patients and staff/practitioners. Health systems should provide long-term, dependable funding for services to ensure sustainability and staff retention.</jats:p></jats:sec>jats:secjats:titleConclusions</jats:title>jats:pWith homelessness on the rise internationally, healthcare systems should focus on high-level factors such as funding stability, building inclusive cultures and setting goals which encourage and support staff to provide flexible, timely and connected services to improve access.</jats:p></jats:sec>