Event centrality refers to the extent to which a personal event in autobiographical memory serves as a reference point for other experiences, as a turning point in the life-story, and is integrated into components of personal identity. Research has shown that event centrality is positively related to symptoms of posttraumatic stress disorder (PTSD). However, limited research is available on the causal relation between event centrality and PTSD symptoms. We examined this causal link in a series of experiments. A pilot test showed that, out of four manipulations, only a cognitive bias modification training of appraisal (CBM-App) decreased event centrality in participants with high event centrality scores. Next, we tested whether the CBM-App training influenced event centrality and PTSD symptoms in a new sample. Participants in the CBM-App condition reported reduced event centrality compared to participants in a non-centrality control condition. No changes in PTSD symptoms were found. The link between event centrality and PTSD symptoms was mediated by posttraumatic cognitions and rumination. Together, these studies suggest that CBM-App training can lower appraisals of event centrality of a distressing autobiographical memory. Long-term effects on PTSD symptoms will need to be tested in future research.