Though Erikson recognized identity development as a lifelong project, most research on identity has focused on adolescents and emerging adults. Less is known about how the identity formed in adolescence is maintained and adapted across the adult life span. The purpose of the present paper is to provide a conceptual review and elaboration of Erikson's (1968) theory focused on identity integration, a construct that is particularly relevant to adult identity development. Identity integration describes the process of bringing together various aspects of one's self into a coherent whole, and the sense of self-continuity and wholeness that emerges as a result of these processes. Informed by the identity and life span development literatures, we present a conceptual framework that describes how identity integration is maintained across the adult life span, and how it is reestablished when changing life circumstances present threats to an individual's identity. These maintenance and reestablishment processes help to support adults' well-being and adaptation to major life transitions and stressful events. This conceptual framework is intended to facilitate research on identity integration in adulthood, a time of life that has been less often studied in the identity literature but that can involve identity dynamics that are just as critical as those in adolescence.