Intergenerational (IG) solidarity is an intentional connection between two or more persons of different age groups. As will be explained and illustrated in this volume, their bonding reflects personal wishes and material goals, emotional bonds and rational justifications, altruism and self-interest, caregiving and care receiving. The study of IG solidarity requires a genuine interdisciplinary approach that can facilitate the intersection of professional expertise in related disciplines, including anthropology, demographics, economics, geriatrics, social psychology, and sociology. This chapter provides an entry point to this study. The goals of the chapter are the following: first, to investigate the meaning of intergenerational solidarity, its dimensions, and its evolution; second, to review the evolution of theoretical perspectives and the establishment of an independent field of IG studies; third, to present a simple model that can be used to assess the complex connections between cultural values, institutions, demographic and socioeconomic dimensions, and the arrangements, both private and public, that societies use to provide care to children and older persons; and finally, to highlight current trends that affect and can be affected by IG solidarity.