The main objective of this study was to evaluate the health action process approach (HAPA) as a motivational model for dietary self-management for people with multiple sclerosis (MS). Quantitative descriptive research design using path analysis was used. Participants were 209 individuals with MS recruited from the National MS Society and a neurology clinic at a university teaching hospital in the Midwest. Outcome was measured by the "Healthy Dietary Stages of Change Instrument", along with 10 predictor measures. The HAPA dietary self-management model fit the data relatively well (goodness-of-fit index = 0.95, normed fit index = 0.90, comparative fit index = 0.95, and root mean square error approximation = 0.07) explaining 15% of the variance in dietary self-management behavior. Recovery self-efficacy and action and coping planning directly contributed to the prediction of dietary health behaviors. Action self-efficacy, outcome expectancy, risk perception, and social support influenced intention, and the relationship between intention and dietary health behaviors is mediated by action and coping planning. Action self-efficacy, maintenance self-efficacy, and recovery self-efficacy directly or indirectly affected dietary health behaviors. Empirical support was found for the HAPA model of dietary self-management for people with MS. The HAPA model can be used to design behavioral health promotion interventions for people with disabilities in vocational rehabilitation. (Contains 2 tables and 3 figures.)