In the present study we report: (1) normative data on the Spanish version of the Anxiety Sensitivity Index (ASI); and (2) empirical evidence related to differentiation between the constructs of anxiety sensitivity and trait anxiety. A sample of 390 university students (ranging in age from 18 to 34 years) completed the ASI and Spielberger's Trait Anxiety Scale (STAI-T). The means and standard deviations for the Spanish version of the ASI are similar to the ones reported by Peterson and Reiss (Anxiety Sensitivity Index Manual, 2nd edition. Worthington, OH: International Diagnostic Systems, 1992) for the English version. Factor analysis of the joint ASI and STAI-T items yielded two different factors; the STAI-T items load onto one factor (i.e., the trait anxiety factor) and the ASI items load onto the other factor (i.e., the anxiety sensitivity factor). Findings provide empirical support for validation of the Spanish ASI and are consistent with a construct distinction between anxiety sensitivity and trait anxiety.