The world’s population is now aging at an unprecedented rate. Fertility decline together with urbanization were the dominant global demographic trends during the second half of the twentieth century, much as rapid improvements in life expectancy characterized the early 1900s. As we move through the first decade of the twenty-first century, population aging has emerged as a major demographic worldwide trend. Declining fertility and improved health and longevity have generated rising numbers and proportions of the older population in most of the world. As education and income levels rise, increasing numbers of individuals reach older age with markedly different longevity and personal expectations then their forebears.