The definition of a traumatic event in Criterion A for posttraumatic stress disorder (PTSD) was narrowed in DSM-5 for events involving indirect exposure to the death of a loved one. Whereas the DSM-IV definition encompassed the sudden, unexpected death of a loved one regardless of the circumstances, the DSM-5 definition now requires that the death must have involved some type of violence or accident. Although there is some support in the literature for this more restrictive definition, its effects are relatively unknown. The purpose of the present study was to examine the impact of this more restrictive definition on the prevalence of Criterion A and the symptom profile of individuals meeting the DSM-IV versus the DSM-5 definition. In two samples of trauma-exposed college students, ordinal logistic regression was used to compare participants with either indirect exposure to a sudden, unexpected death (SUD); indirect exposure to a violent or accidental death (VAD); or direct exposure to a severe motor vehicle accident (MVA). PTSD symptoms were assessed using DSM-IV criteria in Sample 1 and DSM-5 criteria in Sample 2. Results indicated that the more restrictive DSM-5 definition reduced the prevalence of those meeting Criterion A for events involving the death of a loved one. However, few significant differences were found between SUD and the two trauma groups meeting DSM-5 Criterion A (i.e., VAD and MVA) when compared on individual PTSD symptoms, PTSD symptom clusters, and other measures of psychopathology. Diagnostic and research implications regarding the Criterion A change are discussed. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]