In the nearly three years that have elapsed since our first Philadelphia Symposium on Aging, our activities and interactions have expanded. We spent no small amount of time discussing the selection of a timely topic for our next symposium. For the first symposium, a variety of topics relating to the study of aging, ranging from phenomena at the cellular level to phenomena in disease states, were selected for consideration. For the present symposium, we thought it more desirable to concentrate on one area only, in order to summarize available information, discover what shortcomings exist, and suggest new directions for research. The paucity of information on pharmacological studies in aging and the compelling necessity for these studies made it clear to us that the time was appropriate for a review of this subject matter. The approach was to consider topics related to the effects of aging on the basic properties of drug action and on the effectiveness of drugs used in the therapy of diseases in several organ systems. Furthermore, it was felt that by considering the various pharmacological methods of intervention in the aging process, greater insight into the nature of aging would emerge. For the symposium, we brought together 13 outstanding workers in the field of pharmacology to discuss the selected topics. We expect that the chapters will be informative to workers in pharmacology and in biomedical disciplines in general, as well as provide a firm foundation for future work in this exciting area.