1990s (Featherman, Lerner, and Perlmutter, 1994). These volumes provided a conceptual framework for the psychological and sociological study of human development across the full life span. As the empirical literature grew and fed back into theory, general conclusions about aging began to crystallize (see Baltes, 1991). One reliable observation is that the balance between gains and losses—albeit weighted increasingly toward loss—continues to include growth in old age (Heckhausen, Dixon, and Baltes, 1989). Of particular relevance to this report, social relations and emotional well-being appear to be areas typified by growth. Indeed, self-knowledge, well-honed skills in self-regulation, and stable social relationships may represent the very resources on which people draw on in order to face the challenges of aging.

One important theme that runs throughout the literature on social aging concerns selection. Choices made throughout life to pursue intimate relationships, professions, families, and avocations make people focus increasingly on specific individuals and narrower life domains. Throughout adulthood, people actively construct skills and hone environments to meet selected goals. People become increasingly sure about who they are and more accepting of their strengths and weaknesses. The investment of resources in selected domains of life means that these same resources cannot be allocated elsewhere. In other words, breadth is sacrificed for depth. The meta-model of what is called selective optimization with compensation, developed by Baltes and Baltes (1990; see also Baltes, 1997; Freund and Baltes, 1998), views development as increasingly optimized on expert performance in selected domains. In the context of this model, the relative strength of social ties, satisfaction with relationships, and generally good mental health (as discussed below) very likely represent optimization in selected domains.

Of course, development is not driven purely by choice. Selections are also made by outside forces that place people on particular paths and offer limited opportunities. Sociologists refer to the “Matthew effect” (Merton, 1968) to describe the cumulative advantages and disadvantages associated with the roles assigned to individuals as a function of gender, race, and socioeconomic status (Dannefer, 2003). Furthermore, the longer life expectancy of women compared to men and the significant increases in the culturally and racially diverse populations in the United States speak to the critical importance of understanding how gender, race, culture, and ethnicity affect aging. The number of people ages 80 and over will increase by 2030 to more than 19.5 million—a doubling of the current population, and 63 percent will be female. Current projections also suggest that by 2050 the total number of non-Hispanic whites ages 65 and over will nearly double, the number of blacks ages 65 and over will more than triple, and the number of Hispanics will increase almost ten-fold (U.S. Census Bureau, 2004a).