Mark R. Rosenzweig and Oded Stark extend their thanks to authors who were waiting (while updating) patiently for their fellow authors to complete the write-ups of their drafts. They will know that their's and author's efforts were worthwhile if the Handbook of population and family economics contributes to increasing the population of economists involved in research on population and the family, and if the family of social science disciplines adopts the thinking of economists on population and family issues.