Differential diagnosis of autism spectrum disorder (ASD) among intellectually-able adults often presents a clinical challenge, particularly when individuals present in crisis without diagnostic history. The Personality Assessment Inventory (PAI) is a multiscale personality and psychopathology instrument utilized across clinical settings, but to date there are no published normative data for use of the PAI with adults with ASD. This study provides normative PAI data for adults diagnosed with ASD, with effect size comparisons to the PAI clinical standardization sample and an inpatient sample. Additionally, a discriminant function was developed and cross-validated for identification of ASD-like symptomatology in a clinical population, which demonstrates promise as a screening tool to aid in the identification of individuals in need of specialized ASD assessment.