This chapter presents a summary of the career of Richard M. Lerner within the field that, during his professional life, changed its label from child psychology to developmental science. Lerner summarizes the influence of the scholars and the ideas they championed in shaping the breadth of his career, from his days as a doctoral student at the City University of New York in the late 1960s and early 1970s to the more than a quarter century he spent at Tufts University, where he served as the Bergstrom Chair in Applied Developmental Science and Director of the Institute for Applied Research in Youth Development. Lerner explains how the idea of mutually influential coactions between individuals and contexts (i.e., individual⬄context relations) found its roots in the comparative psychology work of T. C. Schneirla and evolved to become embedded in relational developmental systems-based models that emphasize the dynamic character of human development across the life span.