Hooking up, or casual "no strings attached" sexual encounters, has become the normative heterosexual relationship on college campuses. This phenomenon has only recently received public attention. Many citizens have become alarmed that this trend is indicative of moral decline in our culture, a reflection of our hypersexualized media, and a promotion of sexual irresponsibility. However, this is not necessarily so, and researchers have come to identify both social and psychological factors that have produced and continue to maintain this sexual environment on campuses. This paper will review some factors that previous research has discussed, including the shift in intimacy over the past century, social norms enforced by peer groups, psychological attachment style, and the developmental transition period between adolescence and adulthood. Implications for students and psychotherapists who work with students will be discussed.