The prestigious group of scholars assembled for this thirty-ninth volume of the Nebraska Symposium on Motivation address important issues in Psychology and Aging. In the first chapter, James E. Birren and Laurel M. Fisher consider slowness of behavior as a general condition often associated with advancing age and explore its implications of a wide range of hierarchical functions. In succeeding chapters Martha Storandt assesses memory-skills training for older adults, and Irene Mackintosh Hulicka offers, in a previously unpublished G. Stanley Hall lecture, cogent reasons for teaching about aging in psychology classes and procedures for doing so. Challenging the view that cognitive aging is identical with decline, Paul B. Baltes, Jacqui Smith, and Ursula Staudinger adopt the hypothesis of simultaneous growth and decline and relate it to wisdom. Trait psychology is discussed by Paul T. Costa, Jr., and Robert R. McCrae, who review the most recent advances and present new data from longitudinal studies. K. Warner Schaie and his colleagues describe problems and methods of studying natural cohorts within a longitudinal study and report the first data on adult parent-offspring similarity determined as a function of the age of the pair when studied. A commentary chapter by Ross A. Thompson concludes the volume.