Chronic-disease engagement is often treated as an individual attribute although participation depends on psychological capability, relationships, resources, care organization, and digital access. To synthesize psychological, social-relational, and contextual determinants of engagement while distinguishing activation, self-management, adherence, decision participation, and clinical outcomes. A PRISMA-informed review used the documented search record. Aggregate record-return, screening, and eligibility totals were not preserved and were not inferred. Thirty-five substantive evidence reports entered synthesis; four additional references served methodological or discussion functions. Heterogeneous evidence was synthesized without meta-analysis. Engagement-related evidence clustered around capability and appraisal, relational support and permission, and contextual opportunity or constraint. Determinant effects varied with illness demands, life stage, culture, resources, organization, and technology context. Engagement is better interpreted as a context-dependent care state than a fixed patient trait. Multilevel assessment is warranted, while causal claims remain limited by heterogeneous evidence.
