Until recently, the Arab world's primary demographic problem has been the persistence of high fertility, which has contributed to rapid rates of natural increase and produced excessively high dependence ratios, with a large percentage of the population yet to enter reproductive age and join the labor force. However, fertility rates have fallen sharply in most countries and rapid rates of natural increase have abated. Paradoxically, this decline in fertility will combine with increases in longevity to create another perhaps equally serious demographic problem in the near future: a rapid aging of the population. While this phenomenon has largely been associated with mature industrial countries like Japan and Italy, Arab countries also face a dramatic shift in their age structure. In 2000, only 5.5 percent of the population in twenty two Arab countries was over the age of 65. By 2050, this is projected to increase to almost 15 percent. Countries that have experienced the sharpest drop in fertility will experience the most rapid aging: in Lebanon and Tunisia, potentially one of every four people will be over 65 by 2050, while in Egypt, Morocco, and Algeria the figure could exceed one in every five. Although extended family structures and multi-generational households will ensure that the elderly will be cared for, few Arab countries are prepared for a shift of this magnitude. Health care systems will be particularly burdened as morbidity and epidemiological patterns change and degenerative diseases increasingly supplant infectious ones. Once again, most countries will face high dependence ratios, this time because the working age population is supporting so many people over 65 rather than under 15. This paper documents the forthcoming shift in age structure with population pyramids and other illustrative charts and examines some of its social and economic implications. Because so much of its content can best be exhibited graphically, the material lends itself particularly well to a poster presentation.