BACKGROUND: Early intervention vocational rehabilitation (EIVR) is used to optimize return to work (RTW) outcomes for people following spinal cord injury (SCI). However, theoretical clarity is required about how EIVR works, for whom and under what circumstances. OBJECTIVE: To develop a theoretical understanding of how people respond to EIVR following SCI and the contexts in which mechanisms of intervention effect are likely to be activated. METHODS: Realist research methods were used to analyze interviews with 30 participants who had received EIVR following SCI. RESULTS: We conceptualized the reporting of our analyses using a travel metaphor, encapsulating the types and degree of wayfinding support participants required to think about, plan and action their vocational aspirations. Developing, maintaining and enacting hope, supporting self-identity and vocational identity, and focusing on environmental context adaptations required to enact vocational aspirations, appear to be critical mechanisms of intervention effect within EIVR. CONCLUSIONS: Various contexts and mechanisms of EIVR contribute to successful negotiation, achievement and sustainability of RTW outcomes for people following SCI. These theoretical understandings can refine EIVR service provision within SCI rehabilitation and inform how EIVR can improve RTW outcomes for people with acquired neurological conditions in other rehabilitation contexts.