Sequelae of acquired brain injury (ABI) require adjustment processes in which survivors must strive to regain subjective well-being (SWB) in the face of chronic impairment. The current study investigates whether the self-concept of achievement mediates this process. Thirty-five post-acute patients with ABI were assessed neuropsychologically for performance in memory, attention, concept formation and reasoning. Data concerning subjective complaints in applied cognition, self-concept, and SWB were collected. Patients rated their self-concept more negatively compared to a normative sample. Effects of subjective complaints in applied cognition on SWB were mediated by the self-concept of achievement. Contrary to expectations, objective cognitive deficits demonstrated no independent significant relationship to self-concept of achievement or SWB in multiple regression modelling when subjective complaints in applied cognition were considered simultaneously. The findings highlight the necessity of considering patients' subjective complaints and self-concepts to improve rehabilitative progress. Potential implications for neuropsychological rehabilitation are discussed.