The world has made remarkable progress in maintaining adequate food supplies during the past quarter century by introducing yield-increasing technologies such as better genetics, crop protection products, and more efficient use of fertilizers and irrigations. Far more people depend on irrigation in the modern world than during the times of ancient Sumeria. The spread of irrigation has been the key factor in increasing global crop yields. But future scarcity present the single biggest threat to future food production. The shift of water from agriculture to the growing cities and industry almost certainly will impact global food production. This means that dryland agriculture will be increasingly important in meeting food requirement for the growing population. Advaces in plant genetics and agronomic conservation technologies, when considered in concert, continue to provide the greatest opportunities to achieve sustainability and profitability in dryland agriculture and will continue to be the focus of the ARS research program. The ARS is please to join the crop Science Society of America and international center for Agriculture Research in Dry Areas (ICARDA) in sponsoring a symposium Challenges and strategies for Dryland Agriculture at the Trisocieties Annual Meeting in November 2002 at Indianapolis, IN. This special publication contains an impressive series of paper by international group of experts on dryland agricultural production, conservation, and policy. The principles, philosophies, and technologies presented in this publication have the potential to contribute to improve food security and livelihoods for the people in dryland regions of the world.