This study assesses the psychometric properties of three self-report measures of autistic-like tendencies in the general adult population: autistic spectrum quotient (AQ), adult repetitive behaviours questionnaire-2 (RBQ-2A), and systemizing quotient (SQ). Three rounds of development and testing using different U.S. and global samples led to three instruments that are psychometrically sound, parsimonious, and generalizable across populations. The resulting AQ-9, consisting of two factors: social communication and attention to detail, now mirrors the current dual diagnostic criteria in the DSM-5. The RBQ-2A-R has now been refined through CFA for the first time. The new SQ-7 scale also has updated content. All three refined scales demonstrate satisfactory psychometric validity and parsimony and now provide evidence of their appropriateness for empirical research.