The Acceptance of Chronic Health Conditions Scale was developed to measure acceptance in chronic health conditions like multiple sclerosis (MS) and has been translated into Swedish (The Swedish Acceptance of Chronic Health Conditions Scale). The purpose of the present study was to evaluate construct validity and test-retest reliability of the Swedish Acceptance of Chronic Health Conditions Scale in a sample of 138 people with MS. Predefined hypotheses about relationships between the Swedish Acceptance of Chronic Health Conditions Scale and other measures, and the scale's ability to differentiate between groups were explored. Evaluations of reliability and measurement error were performed for both Swedish Acceptance of Chronic Health Conditions Scale sum scores and individual items. Most (78%) a priori formulated construct validity hypotheses were confirmed. Reliability was considered good (intraclass correlation coefficient = 0.80, and weighted kappa values ranging from 0.29 to 0.74). Measurement errors were acceptable (standard error of measurement 3.3 points, limits of agreement -7.5 and 10, and percentage agreement ranging from 42% to 58%). The findings give evidence of both satisfactory construct validity and test-retest reliability and indicate that the Swedish Acceptance of Chronic Health Conditions Scale can be considered for use in both research and clinical practice.