We investigated attachment differences in the perception of facial emotion expressions. Participants completed a dimensional assessment of adult attachment and recognition accuracy tasks for positive and negative facial emotion expressions. Consistently, avoidant participants who were in romantic relationships, in comparison to singles, had lower decoding accuracy for facial expressions of positive emotions. The results were in line with the hypothesis that being in relationship functions as a naturalistic prime of avoidant persons' defensive tendency to ignore affiliative signals, facial expressions of positive emotion in this instance. The results inform emerging research on attachment and emotion perception by highlighting the role of perceivers' motivated social cognitions.