Is psychological aging best understood from an overall structural (systemic) level or in terms of specific processes and mechanisms? Our response to this question lies not in pursuing one or the other approach but in making efforts to join these different levels of theorizing and analysis. Propositions derived from an interdisciplinary integration of evolutionary and ontogenetic arguments provide a guiding framework for questions about the phenomena of aging as well as the design and interpretation of research. They are sufficiently general to be operationalized in the context of specific areas of functioning (e.g., intelligence, self-regulation) and across disciplines. (from the chapter); Research on very old age undertaken in the Berlin Aging Study (P. B. Baltes & K. U. Mayer, in press; Mayer & Baltes, 1996) represents one instantiation of the framework involving the disciplines of sociology, geriatric medicine, psychiatry, and psychology. In this spirit, findings from this study of a heterogeneous sample of 516 men and women between the ages of 70 and 100+ yrs is used to illustrate aspects of the overall framework. (PsycINFO Database Record (c) 2007 APA, all rights reserved)