The objective of this study was to adapt and validate the abbreviated version of the “Autism-Spectrum Quotient” (AQ-Short) in a sample of Spanish native adults. A total of 46 individuals with ASD, 41 ASD-relatives, 17 patients with schizophrenia spectrum disorders and 190 non-clinical adults were administered the Spanish version of the AQ-Short. The results of the confirmatory factorial analysis found two high-order factors (Social Behaviour and Numbers/Patterns) and four subscales (Social Skills, Routines, Switching and Imagination). The reliability analysis showed very good internal structure and test–retest reliability. The AQ-Short also showed moderate convergent validity with ADOS-2. Differences by group were found in the ASD group when compared to other groups. Gender differences were only found in the non-clinical group.