This study examines relations between acceptance as defined in Acceptance and Commitment Therapy (ACT) and adjustment to multiple sclerosis (MS). A first step in this investigation was the development of a measure of acceptance of MS called the MS Acceptance Questionnaire (MSAQ). Consistent with prior findings and theoretical propositions, it was predicted that acceptance would be associated with better adjustment to MS (lower distress and higher positive affect, life satisfaction and marital adjustment and better health). A total of 128 persons with MS completed measures of demographics, illness and adjustment at Time 1 and measures of acceptance and adjustment 12 months later (Time 2). Factor analyses of the MSAQ revealed two factors, action and willingness. Associations between the MSAQ and other validated acceptance measures supported convergent validity. As predicted, after controlling for the effects of initial adjustment and relevant demographic and illness variables, greater acceptance was related to better adjustment, although the action factor emerged as the strongest predictor of better adjustment. This is the first study to examine the role of acceptance (as defined in ACT) in adjusting to MS over time and as such provides a first step for further investigation of acceptance in MS.