There are both gains and losses in cognitive functioning with increased age. Most of the gains occur in aspects of knowledge and acquired information, whereas losses have been documented in measures of the efficiency of processing at the time of assessment. Among the questions that we are interested in are: 1. What are the proximal determinants of age-related effects on cognition? That is, are some aspects of cognitive functioning more fundamental than others with respect to age-related influences? 2. How are age-related influences on cognitive variables organized? and 3. What factors moderate the effects of aging on cognitive functioning?