Background. The Well-being Questionnaire (W-BQ) has been designed to measure psychological well-being in people with a chronic somatic illness and is recommended by the World Health Organization for widespread use. However, studies into the factor structure of this instrument are still limited and their findings are inconsistent. This study aimed to investigate the factor structure of the Dutch version of the W-BQ. Methods. A cross-validation design was used. A total of 1472 people with diabetes completed the W-BQ and were randomly assigned to group A or B. In group A (N = 736), exploratory factor analyses were conducted. Group B (N = 736) was split up into four subgroups of male or female patients with type 1 or type 2 diabetes. In these subgroups, confirmatory factor analyses were employed to test the model(s) developed in group A and the two models described in the literature (four-factor model with 22 items and a three-factor model with 12 items). Results. Exploratory factor analyses yielded a three-factor model with 21 items (negative well-being, energy and positive well-being). In the subgroups of group B confirmatory factor analyses only accepted the three-factor model with 12 items. This factor solution was stable across gender, type of diabetes and level of education. Conclusions. The best description of the factor structure of the Dutch translation of the W-BQ was given by a three-factor solution with 12 items (W-BQ12), measuring positive well-being (four items), negative well-being (four items) and energy (four items).