This research considers how communication within college student social networks may encourage high-risk sexual relationships. Students (n = 274) described sexual scripts for hooking up and reported on peer communication, sexual behavior, and sexual attitudes. Students described varied hookup scripts, expressed ambivalent attitudes, and reported moderate participation in hookups overall. However, the most common hookup script, suggesting high-risk sexual activity (i.e., unplanned, inebriated sex), was featured in most accounts of students who themselves participated in hookups. Students overestimated how often others were hooking up, and these estimates were especially inflated by students who frequently talked about hooking up with friends. Among students with strong ties to peers, frequent peer communication about sex predicted participation in hookups and favorable attitudes about hooking up. Peer approval also predicted hookup behavior and attitudes.