The developmental study of purpose has flourished in the early years of the 21st century. Building on writings about purpose in adulthood, our research team at Stanford has explored the acquisition of purpose among adolescents and young adults living in several parts of the United States. Colleagues in other universities in many parts of the world have studied the development of purpose among populations of adolescents and emerging adults from an array of social and cultural backgrounds. From this growing body of research has emerged a clear picture, international and multicultural in scope, of how purpose is acquired and sustained; how it functions; how the capacity for purpose develops over the lifespan; and how it relates to other psychological capacities. We also are gaining knowledge about why many individuals do not acquire full (or even partial) capacities for dedicating themselves to purposes, and of the consequences of a lack of purpose for personal well-being and moral commitment. In this chapter, we review findings that have contributed to this knowledge; and we present our views on what is known at this time and what is yet to be discovered.