Work teams have been in use for many years, yet research-based knowledge of the keys to high performance still has questions to answer. The development or maturity of a team is assumed to be closely related to the level of performance, but few studies have examined the maturation process thoroughly. Models of that process have emerged over the past half century, but their value seems limited. The chapters in this volume provide ideas, examples, and frameworks for improving our understanding of team development and the models we follow in fostering that development. As ideas like these become incorporated in research and practice, our ability to effectively move a team toward advanced levels of maturity will improve, and with that will come more frequent successes where teams outperform expectations.