This chapter focuses on fertility and birth rates, mortality and death rates, migration into and out of countries, with a special focus on the effect of an increasingly elderly population that has changed the composition of the United States. There is a clear decrease in fertility rates for the largest racial and ethnic groups, including Latinas, Black non-Hispanics, and Asian Americans. Long term trends in fertility are driven by broader societal forces such as economic development, employment rates, cultural norms, women's education, and access to quality birth control. Longer life expectancy combined with the aging of the US population is one of the most important demographic shifts of the twenty-first century. Thus, the demographic profile of the rapidly aging elder population holds diverse concerns regarding the unique needs and/or challenges that arise at different ages. The changes brought about by population fluctuations create new meanings of identity, whether national, ethnic, or personal.