This article examines how blood donation loyalty changes across the life course as a result of life events. Previous studies have shown that life events affect involvement in prosocial behavior, possibly as a result of loss of human and social capital. Using registry data from the blood collection agency in the Netherlands, linked to longitudinal survey data from the Donor InSight study (N = 20,560), we examined whether life events are related to blood donor lapse. Childbirth, losing a job, and starting a job increase the likelihood of donor lapse, while health-related events (i.e., blood transfusion in a family member, death of a family member) decrease the likelihood of donor lapse. Moreover, results showed how social and practical concerns explain donors’ decisions to donate blood after the occurrence of life events. We discuss theoretical implications for further studies on prosocial and health-related behavior.