his chapter provides an overview of Southeast Asia's demographic situation over the first fifteen years of this century, and highlights variations across countries. It concludes with discussions of major demographic challenges facing each country in the region. Data for this chapter are taken mainly from the United Nations' World Population Prospects—2015 Revision database. By focusing on this period, this chapter updates and adds to the findings of an article by Gavin Jones1 that provides a comprehensive analysis of the population situation for Southeast Asia from 1980 to 2010.