The purpose of the present study was to shed light on the latent structure and nature of individual differences in anxiety sensitivity (AS) and related risk for psychopathology. The present study evaluated the latent structure of AS using factor mixture modeling (FMM; Lubke and Muthén, 2005) and tested the relations between the observed FMM-based model of AS and psychopathology in a large, diverse adult clinical research sample (N=481; 57.6% women; M(SD)(age)=36.6(15.0) years). Findings showed that a two-class three-factor partially invariant model of AS demonstrated significantly better fit than a one-class dimensional model and more complex multi-class models. As predicted, risk conferred by AS taxonicity was specific to anxiety psychopathology, and not to other forms of psychopathology. The sample was not epidemiologic, self-report and psychiatric interview data were used to index AS and psychopathology, and a cross-sectional design limited inference regarding the directionality of observed relations between AS and anxiety psychopathology. Findings are discussed with respect to the nature of AS and related anxiety psychopathology vulnerability specifically, as well as the implications of factor mixture modeling for advancing taxonomy of vulnerability and psychopathology more broadly. Copyright © 2013. Published by Elsevier B.V.