This article provides the rationale for doing research on childlessness and parenthood in late life. Childless older adults have been rendered invisible in the social scientific literature. A central goal of this issue is to make them visible and to expose unstated assumptions about normal adult life. Parenthood emerges as a key organizer of the life course and a major factor in social integration. Because the childless tend to be conceptualized as "the other," focusing on them teaches lessons about the dangers of dichotomous thinking, that is, overlooking diversity and assuming deficiency. Studying older adults without children reveals the necessity of considering life pathways over time and of putting lives in a historical context. (Contains 1 table.)