The autobiographical memory model of posttraumatic stress disorder (PTSD) argues that centralizing a traumatic event into one's life story is a maladaptive process associated with increased PTSD symptoms. Current measures of event centralization make no reference to whether individuals centralize the event in a positive or negative way. This study examined 400 undergraduate participants using a modified version of the Centrality of Events Scale composed of 2 factors measuring both positive and negative event centralization. Exploratory factor analysis confirmed the 2-factor structure. Negative event centralization was associated with PTSD symptoms to a greater degree than was positive event centralization, and negative event centralization mediated the relationship between neuroticism and PTSD symptoms. Combined, these results suggest that the effect of event centralization is dependent on the valence with which the individual centralizes the event. The relationship shown between negative event centralization and PTSD symptoms supports the autobiographical memory model of PTSD.