This volume outlines the status of fundamental physics at the threshold of the 21st century. Some of the world's leading theorists and experimentalists discuss ongoing research on the following topics: M Theory, Superstring Theory, Supersymmetry and Supergravity, Quantum Gravity, Dark Matter in the Universe, Gravitational Radiation, Proton Decay, Higgs Physics, Cosmology, Bose-Einstein Condensation.