The aim of present study was to investigate the mediating role of identity processing styles in the relationship between attachment styles and cognitive emotion of regulation. Participants included 378(253 females and males 125) selected from Shiraz University students selected by multistage random cluster sampling method. The research instruments were Attachment Styles Scale (Gillath, Hart, Noftle, & Stockdale, 2009), Identity Styles Scale (ISS-6G, White, Wampler & Winn, 1998) and Cognitive Emotion of Regulation Questionnaire (Granefski, Kraaij & Spinhoven). Findings showed that secure attachment had indirect effects on positive and negative cognitive emotion of regulation strategies by mediation of informational identity style and by mediating of normative identity style had an indirect effect on positive cognitive emotion regulation strategies. Ambivalent attachment had indirect effects on positive emotion regulation by mediation of informational and normative identity styles and on negative emotion regulation strategies by informational identity style. In addition avoidant attachment showed an indirect effect on positive and negative cognitive emotion regulation strategies by mediation of diffused identity style. Accordingly, identity processing styles played mediating roles in relationship between attachment styles and cognitive emotion regulation.