||The present study examined sex differences in deception detection. One hundred and eleven heterosexual participants (judges) watched videotapes of ten participants (targets) discussing their feelings of attraction and friendship and tried to determine if the targets were lying or telling the truth. On average, it was found that men and women did not differ in their ability to discriminate lies from truths. However, sex differences emerged when male targets were discussing their feelings of attraction. While women were more accurate than men on average, men outperformed women when male targets were lying about attraction. Furthermore, in the attraction context, women needed more evidence to call a male target a liar than men. These findings were explored using accommodation theory and evolutionary psychology.