The factor structure of the Sport Orientation Questionnaire with three factors of competitiveness, win orientation, and goal orientation was examined in a sample of 243 wheelchair athletes from the USA. Based on sample-specific validity evidence theory, it was hypothesized that the exploratory and confirmatory factor analyses would yield evidence on validity for wheelchair athletes who were different from able-bodied athletes. Exploratory factor analysis confirmed the hypothesis with a clear fourth and a questionable fifth factor. A confirmatory factor analysis did not adequately explain the new five-factor model. The new emerging fourth and fifth factors separated the competitiveness element of the questionnaire in 'self-referenced' and 'other-referenced' elements of competitiveness. Results are discussed in terms of demographic characteristics of the sample of wheelchair athletes.