The first National Symposium on Frontiers of Science meeting was held in March 1989 at the Beckman Center in Irvine, California. A second meeting was held November 1-3, 1990. The meetings are designed to bring together a selected group of young U. S. scientists to discuss exciting advances and opportunities in their respective fields in a format that encourages, and allows adequate time for, informal one-on-one discussions among participants. Interaction of the future leaders of U. S. science is intended, inter alia, to stimulate future collaboration in research and the transfer of new techniques and approaches across fields. Speakers focus their talks on current cutting-edge research in their field to a scientifically sophisticated but non-specialist audience and provide a sense of the experimental data--what is actually measured and seen in the various fields. They provide information such as: What are the major research problems and unique tools in the field? What are the current limitations on advances as well as the frontiers? Topics for the November 7-9, 1991 meeting include: aging, AIDS and AIDS transmission, biological structure, immunology, materials chemistry, protein structure and folding, evolutionary biology, particle physics, nuclear physics, the Sun, dark matter, cosmic wave background, planetary science, mass extinctions, oceanography, global change, earthquake science and prediction, artificial intelligence, combinatorial algorithms, computational geometry, micromachining, laser atom trapping, scanning tunneling microscopy, and accelerator mass spectrometry.