The Autism-Spectrum Quotient (AQ) is among the most widely used scales assessing autistic traits in the general population. However, some aspects of the AQ are questionable. To test its scale properties, the AQ was translated into Swedish, and data were collected from 349 adults, 130 with autism spectrum disorder (ASD) and 219 without ASD, and analysed with Rasch. Several scale properties of the AQ were satisfactory but it did not meet the criterion of a unidimensional measure of autistic traits. The Rasch analysis showed that the 50-item AQ could be reduced to a 12-item subset with little loss of explanatory power, with the potential to efficiently measure the degree to which adults with and without ASD show autistic traits.