This study examines the anxiety sensitivity construct by investigating predictive and incremental validity of the CASI in a sample of normal children aged 9 to 11 (N= 151). Participants completed the Spanish versions of the Childhood Anxiety Sensitivity Index (CASI; Silverman, Fleisig, Rabian & Peterson, 1991), the Fear Survey Schedule for Children-Revised (FSSC-R; Ollendick, 1983), the State-Trait Anxiety Inventory for Children (STAIC, Spielberger, 1970), and a measure of anxiety frequency. Overall, results showed that: (1) anxiety sensitivity and trait anxiety correlate moderately and appear to be separate constructs, (2) anxiety sensitivity is strongly related to fear, and (3) anxiety sensitivity predicts variance of fear above and beyond that predicted by trait anxiety. Findings support the hypothesis that childhood anxiety sensitivity may be viewed as an unique construct of vulnerability to fear. Results are discussed in terms of the usefulness of anxiety sensitivity in children and the Spanish validation of the CASI.