BackgroundHealth insurance has the potential to improve access to health care and protect people from the financial risks of diseases. However, health insurance coverage is often low, particularly for people most in need of protection, including children and other vulnerable populations.ObjectivesTo assess the effectiveness of strategies for expanding health insurance coverage in vulnerable populations.Search methodsWe searched Cochrane Central Register of Controlled Trials (CENTRAL), part of The Cochrane Library. www.thecochranelibrary.com (searched 2 November 2012), PubMed (searched 1 November 2012), EMBASE (searched 6 July 2012), Global Health (searched 6 July 2012), IBSS (searched 6 July 2012), WHO Library Database (WHOLIS) (searched 1 November 2012), IDEAS (searched 1 November 2012), ISI‐Proceedings (searched 1 November 2012),OpenGrey (changed from OpenSIGLE) (searched 1 November 2012), African Index Medicus (searched 1 November 2012), BLDS (searched 1 November 2012), Econlit (searched 1 November 2012), ELDIS (searched 1 November 2012), ERIC (searched 1 November 2012), HERDIN NeON Database (searched 1 November 2012), IndMED (searched 1 November 2012), JSTOR (searched 1 November 2012), LILACS(searched 1 November 2012), NTIS (searched 1 November 2012), PAIS (searched 6 July 2012), Popline (searched 1 November 2012), ProQuest Dissertation &Theses Database (searched 1 November 2012), PsycINFO (searched 6 July 2012), SSRN (searched 1 November 2012), Thai Index Medicus (searched 1 November 2012), World Bank (searched 2 November 2012), WanFang (searched 3 November 2012), China National Knowledge Infrastructure (CHKD‐CNKI) (searched 2 November 2012).In addition, we searched the reference lists of included studies and carried out a citation search for the included studies via Web of Science to find other potentially relevant studies.Selection criteriaRandomised controlled trials (RCTs), non‐randomised controlled trials (NRCTs), controlled before‐after (CBA) studies and Interrupted time series (ITS) studies that evaluated the effects of strategies on increasing health insurance coverage for vulnerable populations. We defined strategies as measures to improve the enrolment of vulnerable populations into health insurance schemes. Two categories and six specified strategies were identified as the interventions.Data collection and analysisAt least two review authors independently extracted data and assessed the risk of bias. We undertook a structured synthesis.Main resultsWe included two studies, both from the United States. People offered health insurance information and application support by community‐based case managers were probably more likely to enrol their children into health insurance programmes (risk ratio (RR) 1.68, 95% confidence interval (CI) 1.44 to 1.96, moderate quality evidence) and were probably more likely to continue insuring their children (RR 2.59, 95% CI 1.95 to 3.44, moderate quality evidence). Of all the children that were insured, those in the intervention group may have been insured quicker (47.3 fewer days, 95% CI 20.6 to 74.0 fewer days, low quality evidence) and parents may have been more satisfied on average (satisfaction score average difference 1.07, 95% CI 0.72 to 1.42, low quality evidence).In the second study applications were handed out in emergency departments at hospitals, compared to not handing out applications, and may have had an effect on enrolment (RR 1.5, 95% CI 1.03 to 2.18, low quality evidence).Authors' conclusionsCommunity‐based case managers who provide health insurance information, application support, and negotiate with the insurer probably increase enrolment of children in health insurance schemes. However, the transferability of this intervention to other populations or other settings is uncertain. Handing out insurance application materials in hospital emergency departments may help increase the enrolment of children in health insurance schemes. Further studies evaluating the effectiveness of different strategies for expanding health insurance coverage in vulnerable population are needed in different settings, with careful attention given to study design.