Background <p>Anxiety sensitivity is a well-established transdiagnostic construct implicated in the onset, maintenance, and relapse of various behavioral health problems. Although the Short Scale Anxiety Sensitivity Index (SSASI) is commonly used as a brief measure of anxiety sensitivity, further psychometric evaluation is needed, particularly among populations of diverse racial and ethnic backgrounds.</p> Methods <p>Participants with elevated symptoms of anxiety and/or depression from the United States were recruited into a 6-month randomized clinical trial that compared two digital therapeutics during and after the COVID-19 pandemic. The factor structure, measurement equivalence, and reliable change of the SSASI were assessed.</p> Results <p>Participants (<i>N</i> = 822) were of diverse racial and ethnic backgrounds with elevated anxiety and/or depression (<i>M</i>_age = 38.34, <i>SD</i> = 12.76). Overall, 206 (25.1%) identified as African American, 208 (25.3%) as American Indian, 202 (24.6%) as Latinx, and 206 (25.1%) as non-Latinx White. Results revealed a unidimensional factor structure with residual covariance between two items. Measurement invariance was confirmed across race/ethnicity, sex, and time points. Positive associations were found between SSASI scores and anxiety and depression, respectively. The scale also demonstrated treatment sensitivity, with statistically significant reductions in SSASI observed in the treatment group targeting anxiety sensitivity.</p> Conclusion <p>The current study provides evidence supporting the psychometric properties and clinical utility of the SSASI in individuals from diverse racial and ethnic backgrounds in the context of a digital therapeutic intervention.</p>