Objective: The aim of this study was to identify the principal determinants that are longitudinally associated with the performance of social roles in the first 3 years following a diagnosis of multiple sclerosis. Design: Inception cohort with 5 measurements over 3 years. Patients: A total of 156 patients recently diagnosed with multiple sclerosis. Method: Performance of social roles was measured using the 2 role functioning and the social sub-scales of the Medical Outcome Study Short Form 36. Potential determinants (n = 43) were divided into the following clusters: patient and disease characteristics (n = 12), psychosocial characteristics (n= 10), basic functions (n= 18) and basic activities (n= 3). Multivariate longitudinal regression analyses were performed with generalized estimating equations. A backwards selection procedure for every cluster per outcome reduced the large number of potential determinants. In order to determine whether longitudinal associations are present the selected determinants were entered into an overall regression model. Results: Twenty-three candidate determinants were selected. Vitality, measured with the SF36 sub-scale vitality, the T2-weighted supratentorial lesion load and the perceived amount of social support, measured with the Social Support List Discrepancies, were longitudinally associated with the performance of social roles in 2 or 3 of the models. Conclusion: Vitality, the perceived amount of social support, and disease activity, i.e. the T2-weighted supratentorial lesion load, determine the performance of social roles in the early stages of multiple sclerosis. © 2007 The Authors. Journal Compilation © 2007 Foundation of Rehabilitation Information.