The factor structure of the Childhood Anxiety Sensitivity Index (CASI) was investigated in four nonclinic German samples (N=1244, 225, 230, and 143) with participants aged 8-16-years-old. Factor solutions suggested for different CASI versions were tested using confirmatory factor analysis. The best goodness-of-fit indices were found for the 13-item CASI version with 4 factors (Disease Concerns, Unsteady Concerns, Mental Incapacitation Concerns, and Social Concerns). Testing for factorial invariance of this model with respect to age and gender revealed non-invariant factor loadings between children and adolescents as well as between boys and girls. The theoretical and clinical implications of these findings for anxiety sensitivity in children and adolescents are discussed.