Useful Knowledge: What will it be for the next millennium? In five symposia, members of the Amer. Philosophical Soc. asked this question in April 1999 at the Society's Millennium Meet. Contents: (1) Math & Physical Sciences: The Laws of Nature, Our Concepts of the Cosmos, Progress, Prospects & Mysteries, Math & Computing, Global Warming: Does Science Matter?, & The Molecular Biology of Huntington's Disease, (2): Biological Sci.: Scientists & the Public: An Ambivalent Partnership, Cancer: The Revolution & the Challenges, Wiring the Brain: Dynamic Interplay between Nature & Nurture, & A Neuroscience of Memory for the 21st Cent., (3) Social Sci.: Nat. Sovereignty & Human Rights, Econ. Becomes a Science -- Or Does It?, & A Millennium of Economics in Twenty Minutes: In Pursuit of Useful Knowledge, (4) Humanities: Art & Architectural History in the 20th Cent., More Than One Millennium: The Perennial Return of the History of Religions, & Singularity in an Age of Globalization, & (5) The Professions, Arts & Affairs: 100 Yrs. of the Renaissance, Race & Admission to Univ., Health Care in a Democratic Soc., & Culture & Democracy in America. Illus.