Criterion A has been controversial since its inception, partially because it performs a key gate keeping function. Major criticisms of Criterion A of the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV; American Psychiatric Association, 1994) include that it has resulted in “criterion creep.” The authors tested the hypothesis that a nonrestrictive definition would substantially increase posttraumatic stress disorder (PTSD) prevalence by determining PTSD based on Criteria B, C, D, E, and F, without restricting Criterion A in large probability samples of U.S. adolescents and Florida adults. Few PTSD cases occurred in the absence of Criterion A1 events, providing little support for the criterion creep hypothesis. Specific recommendations are to retain Criterion A; permit additional events; consider expanding Criterion A2; consider that either Criterion A1 or A2 be met; and place greater emphasis on Criterion F.