Objectives: Primary: To gain a system-wide perspective on factors leading to athlete attrition from a high-performance sport system (HPSS). Secondary: To identify what a sample of system-wide stakeholders and past athletes value as the most important and feasible attrition factors to address to retain talented athletes. Design: Mixed-methods. Methods: Concept mapping was used for qualitative data collection and quantitative data analysis. Sixty-one participants including: (i) past athletes from an Australian state sporting institute; (ii) their families; and (iii) internal and external stakeholders to a HPSS who supported past athletes. Results: Participants brainstormed 83 unique statements (i.e. attrition factors) that were mapped into 13 clusters of attrition factors following multidimensional scaling and hierarchical cluster analysis performed on the participants sorting data: ‘abuse and mismanagement of health’; ‘athlete health’; ‘limited support/resourcing’; ‘coaching’; ‘inconsistent processes’; ‘financial and career support’; ‘pathway structure’; ‘organisational dynamics’; ‘competitive stress’; ‘performance potential’; ‘challenges with selection and transition’; ‘psychological state’; and ‘competing non-sport priorities’. ‘Abuse and mismanagement of health’ had the highest mean importance (3.76 out of 5) and feasibility (3.31) rating. The 13 clusters were further grouped into four overarching domains: ‘sport system policy, structure and processes’; ‘pathway structure, transition and support’; ‘individual athlete health and capability’; and ‘whole-of-life demands and priorities’. The domain ‘sport system policy, structure and processes’ contained the most important and feasible clusters. Conclusions: Macro (system-level) and micro (intrapersonal and interpersonal) level athlete attrition factors should be considered together. Athlete health was considered the most important athlete retention issue to address.