Legitimacy, embedding, and learning framework: lessons from individual placement and support for analyzing sustainment and scale-up of complex psychosocial interventions.

OBJECTIVES: To develop a framework of policy-level domains for analyzing the sustainment and scale-up of Individual Placement and Support and, tentatively, other complex evidence-based psychosocial interventions. METHODS: Integrative review of 41 empirical studies on contextual determinants of Individual Placement and Support (IPS) sustainment and scale-up was conducted. The results were synthesized inductively and interpreted abductively using implementation science, policy implementation research, and welfare policy literature. RESULTS: The LEL framework organizes recurring external-context patterns into three policy-level domains: Policy Legitimacy addresses policy legitimization and decision chains linking high-level policy decisions to implementation; Policy Embedding addresses multi-level and cross-sector implementation structure; and Policy Learning addresses implementation evidence infrastructure through which implementation experience informs practice, policy, and model refinement. CONCLUSION: The Legitimacy-Embedding-Learning (LEL) framework proposes policy-level domains for analyzing IPS sustainment and scale-up. It functions as an integrative analytical framework that supports cumulative evidence-building and comparative research within IPS, with testable relevance for other evidence-based complex psychosocial interventions.