BACKGROUND: Improvements in care and treatment have led to more young adults with life-limiting conditions living beyond childhood, which means they must make the transition from children’s to adult services. This has proved a challenging process for both young adults and service providers, with complex transition interventions interacting in unpredictable ways with local contexts. OBJECTIVES: To explain how intervention processes interact with contextual factors to help transition from children’s to adult services for young adults with life-limiting conditions. DESIGN: Systematic realist review of the literature. DATA SOURCES: Literature was sourced from four electronic databases: Embase, MEDLINE, Science Direct and Cochrane Library from January 1995 to April 2016. This was supplemented with a search in Google Scholar and articles sourced from reference lists of included papers. REVIEW METHODS: Data were extracted using an adapted standardised data extraction tool which included identifying information related to interventions, mechanisms, contextual influences and outcomes. Two reviewers assessed the relevance of papers based on the inclusion criteria. Methodological rigor was assessed using the relevant Critical Appraisal Skills Programme tools. RESULTS: 78 articles were included in the review. Six interventions were identified related to an effective transition to adult services. Contextual factors include the need for children’s service providers to collaborate with adult service providers to prepare an environment with knowledgeable staff and adequate resources. Mechanisms triggered by the interventions include a sense of empowerment and agency amongst all stakeholders. CONCLUSIONS: Early planning, collaboration between children’s and adult service providers, and a focus on increasing the young adults’ confidence in decision-making and engaging with adult services, are vital to a successful transition. Interventions should be tailored to their context and focused not only on organisational procedures but on equipping young adults, parents/carers and staff to engage with each other effectively.