Despite the well-known association between emerging adults’ attachment security and peer pressure, there is still a dearth of knowledge about the possible intervening mechanisms. The present study aimed to investigate the mediating role of rejection sensitivity in relation to attachment security and peer pressure in Turkish emerging adults. A total of 836 emerging adults (82% female) aged between 18 and 24 (Mage = 21.58, SD = 1.50) were assessed for perceptions about security of relationship with parents by using Kerns’ Security Scale, for rejection sensitivity reports about families and social relationships by using Rejection Sensitivity Questionnaire, and for peer pressure perceptions about social relationships by using Peer Pressure Scale. Data was collected via an online survey. Results of the path analysis on the direct and indirect relationships among study variables showed that attachment security negatively predicted rejection sensitivity, as well as peer pressure. Rejection sensitivity was related positively to peer pressure. It is concluded that there is a significant mediating role of rejection sensitivity in the relation between attachment security and peer pressure. Our findings underscored the necessity of considering individual factors such as rejection sensitivity, when examining the relation between familial and social aspects of emerging adults. Keywords: Attachment theory, attachment security, rejection sensitivity, peer pressure, emerging adults