In this study, the mediator role of adaptive cognitive emotion regulation in the effect of deliberate rumination upon posttraumatic growth was aimed to be analyzed. A convenience sample of 272 university students including 175 (64,3%) females and 97 (35,7%) males was recruited from a university in Denizli, Turkey. Ages of the participants ranged between 20 and 37 with an average age of 21.94 years (SD=1.69). The Posttraumatic Growth Inventory, Event Related Rumination Inventory and Cognitive Emotion Regulation Questionnaire were used for collecting the data. The data were analyzed using SPSS 23 and Amos 22 software packages. Deliberate rumination was determined to be significantly and positively correlated with posttraumatic growth (r=,28, p<,01) and positive cognitive emotion regulation (r=,25, p<,01). Moreover, positive cognitive emotion regulation was significantly and positively correlated with posttraumatic growth (r=,27, p<,01). The results indicated that adaptive cognitive emotion regulation mediated the effect of deliberate rumination on posttraumatic growth. The results, limitations, and implications of the study were discussed.