In this chapter, we review Ornstein’s contributions to the study of children’s memory strategy use to maintain information they are expected to remember, including barriers, supports, and application. We then discuss our own work on how children go beyond maintaining information to extending their knowledge base by going beyond what was explicitly provided and self-deriving new knowledge through integration of separate learning episodes. We examine the parallels in how knowledge is maintained and extended, including the role of prior knowledge. We conclude with three lessons learned from the work of Ornstein and colleagues that will enrich developmental science: move the research into ecologically relevant and even “high-stakes” contexts, conduct longitudinal work, and investigate the role of metacognition.