The present study evaluated sex differences in observational fear conditioning using modeled ''mock'' panic attacks as an unconditioned stimulus (UCS). Fifty-nine carefully prescreened healthy undergraduate participants (30 women) underwent 3 consecutive differential conditioning phases: habituation, acquisition, and extinction. It was expected that participants watching a confederate display mock panic attacks (UCS) paired with a previously neutral stimulus (CS[superscript plus]) would learn to respond fearfully to the CS[superscript plus], but not to the CS[superscript minus] (i.e., a stimulus never associated with displays of panic). Women also were expected to report more distress and ratings of panic to the CS[superscript plus] than the CS[superscript minus] compared to men, but no sex differences were anticipated on autonomic indices of conditioning (i.e., electrodermal responses). Consistent with expectation, aversive conditioning was demonstrated by greater magnitude electrodermal and verbal-evaluative (e.g., subjective units of distress scale, panic ratings) responses to the CS[superscript plus] over the CS[superscript minus], with women reporting more distress to the CS[superscript plus] over the CS[superscript minus], but not greater autonomic conditioning, compared to men. Overall, the results support the notion that modeled panic attacks can serve as a potent UCS for both men and women. Discussion focuses on sex differences in observational fear conditioning and its relation to the clinical presentation of anxiety disorders.