Attachment styles are considered important not only for adults’ close relationships but also for individual’s well-being, reflecting the subjective quality of life, covering positive mood, vitality, and interest in things. Emotion regulation is considered to be in direct relation with these variables and expected to play a mediating role in the association between attachment and well-being. The aim of this study was to obtain better insight into the associations between attachment styles and subjective well- being, by testing the possible mediating role of emotion regulation skill. The methodology employed in this study was descriptive methodology. Sample demographics were 130 students of University of Isfahan, Iran, who were selected based on multi-stage simple sampling method. Direct effects of attachment styles on emotion regulation skill were all significant (p<.05). Direct effects of secure and avoidance styles on SWB were both significant (p<.05). Indirect effects of attachment styles on SWB were all significant (p<.05). Indirect effects of avoidance style on SWB was-0.11, indirect effects of secure style on SWB was 0.4, and indirect effects of ambivalence style on SWB was -.21 (p<.05). Model fit indices were: CMIN/DF= 1.69, GFI= .84, CFI= .96, PCFI= .83, REMSEA= .07, and HOELTER= 91. Emotion regulation skill has the mediating role in the relation between attachment styles and subjective well- being.