The face of aging in the United States is changing dramatically and much of the 21st Century will be defined by population aging (Goldstein, 2010). People are living longer, achieving higher levels of education, living in poverty less often, and experiencing increasingly lower rates of disability. Life expectancy nearly doubled during the 20th Century with a ten-fold increase in the number of Americans age 65 or older. Today, there are approximately 35 million Americans age 65 or older, and this number is expected to double in the next 25 years. The oldest old – people age 85 or older – constitute the fastest growing segment of the U.S. population. Currently about four million people, this population could top 19 million by 2050. And living to 100 is becoming increasingly commonplace. In 1950, there were approximately 3,000 centenarians in the United States. By 2050, there could be nearly one million. The challenge for the 21st Century will be to make these added years as healthy and productive as possible and to continue the current trend of decline in disability across all segments of the population.