The present investigation examined the factor structure, internal consistency, and construct validity of the 16-item Anxiety Sensitivity Index (ASI; Reiss Peterson, Gursky, & McNally 1986) in a young adult sample (n = 420) from the Netherlands. Confirmatory factor analysis was used to comparatively evaluate two-factor, three-factor, and four-factor models of the anxiety sensitivity construct. Support was found for a hierarchical structure of anxiety sensitivity, with one global higher-order factor and four lower-order factors. Internal consistency for the global and lower-order factors of the 16-item ASI was adequate. Convergent and discriminant associations between the 16-item ASI and general mood and panic-specific variables were consistent with anxiety sensitivity theory. In addition, incremental validity of the anxiety sensitivity construct was established, relative to negative affectivity, for unexpected panic attacks and agoraphobic avoidance. (Contains 3 tables and 1 figure.)