PURPOSE: The relevance of self-concept change in the process of psychosocial adjustment following multiple sclerosis (MS) diagnosis has become more apparent in recent years. The current study aimed to investigate the experience of self-concept change as described by an MS sample. METHODS: Sixteen people (aged 26-67 years, 62.5% female) who had been living with MS for an average of 12 years, participated in a single online semi-structured interview. All interviews were audio-recorded and transcribed verbatim. RESULTS: Thematic analysis guided by phenomenology produced three superordinate themes: 1) Changing life (salient external events that were related to changing views of self), 2) Changing self (the experience of self-concept change), and 3) Changing thoughts (the internal thought processes that served as the filter between changing life circumstances and changing self-views). Overall, external events appeared to facilitate a process of internally driven revaluations and redefinitions of self-concept both globally and within specific self domains. CONCLUSION: Self-concept change due to MS emerges as a complex internal process, often arising from external challenges and changes in everyday life. These novel findings illustrate the need to better support people with MS to make sense of changes to their self-concept, particularly during key transitions across the illness.Implications for RehabilitationSelf-concept change following MS diagnosis and throughout the disease course has wide-ranging impacts on psychological adjustment.Several key external events contribute to changing the self-views of people living with MS.While external events prompt change, key internal processes likely facilitate the redefinition of self-concept.Targeted support during key transitional periods to assist pwMS to productively renegotiate and manage these changes to their self-concept is needed.