The collection of chapters in the Handbook of Population and Family Economics and their organization reflect the most recent developments in economics pertaining to population issues and the family. The rationale, contents, and organization of the Handbook evolve from three premises. First, the family is the main arena in which population outcomes are forged. Second, there are important interactions and significant causal links across all demographic phenomena. Third, the study of the size, composition, and growth of a population can benefit from the application of economic methodology and tools. The diversity and depth of the work reviewed and presented in the Handbook conveys both the progress that has been made by economists in understanding the forces shaping population processes, including the behavior of families, and the many questions, empirical and theoretical, that still remain.