In February 2010, the National Research Council convened a workshop to investigate the feasibility of developing well-grounded common metrics to advance behavioral and social science research, both in terms of advancing the development of theory and increasing the utility of research for policy and practice. The Workshop on Advancing Social Science Theory: The Importance of Common Metrics had three goals: To examine the benefits and costs involved in moving from metric diversity to greater standardization, both in terms of advancing the development of theory and increasing the utility of research for policy and practice. To consider whether a set of criteria can be developed for understanding when the measurement of a particular construct is ready to be standardized. To explore how the research community can foster a move toward standardization when it appears warranted. This book is a summary of the two days of presentations and discussions that took place during the workshop.