A large body of research has suggested that anxiety sensitivity (AS) acts as a specific vulnerability factor in the development of anxiety pathology. More recently, attention has turned to the etiology of AS per se. The present study represents a specific test of a Scar model of AS. A Scar model posits that the experience of distress will affect the vulnerability factor. We were specifically interested in evaluating the effects of a specific stressor (spontaneous panic) as well as general distress on changes in AS over time. A large nonclinical sample of young adults (N = 1296) was prospectively followed over a five week highly stressful period of time (i.e. military basic training). Findings were consistent with the Scar model and suggested that the specific stressor of experiencing a panic attack as well as general stressors creating significant anxiety symptoms uniquely contributed to increased levels of AS (regardless of prior history of panic). Moreover, the experience of spontaneous panic in the context of generally low levels of distress (both anxiety and depression) appeared to be particularly pernicious in terms of resulting in greater increases in AS. In sum, anxiety-related stressors appear to have the potential to 'scar' individuals in regard to this cognitive vulnerability factor.