With an ever-increasing demand on blood supplies worldwide, there is an immense need to ensure a safe and sufficient supply of blood products. However, recruiting and retaining blood donors remain key challenges for blood agencies. In an attempt to address these problems, researchers have identified a range of sociodemographic, organizational, physiological, and psychological factors that influence people's willingness to donate blood. Although past research has largely focused on donor recruitment, in particular, demographic variables associated with blood donation behavior, the issue of donor retention has become increasingly important. A growing number of studies have also highlighted the role of psychological factors in explaining, predicting, and promoting blood donation behavior. In line with recent trends in blood donation research, the present article reviews the contributions of, and current directions in, psychological research on blood donation attitudes and behavior, with special emphasis on donor return and repeat blood donation behavior. Although there is overlap between factors that predict the initiation and the maintenance of blood donation behavior, it is suggested that changes in motivation and the development of self-identity as a blood donor are crucial for understanding the processes whereby first-time donors become repeat donors.