The first precision measurements on CP violation in the B system are reported. Both the BELLE and the BABAR collaboration presented, among others, results for sin 2ß with much improved accuracy. Results from the Sudbury Neutrino Observatory, SNO, also deserve to be mentioned. The convincing evidence of solar neutrino oscillations had been presented by SNO prior to the conference; a full presentation was given at the conference. An incredibly precise measurement of the anomalous magnetic moment of the muon is reported, a fresh result from the Brookhaven National Laboratory. Apart from these distinct physics highlights, there are also the first results from the new Tevatron run and from the relativistic heavy ion collider RHIC. Theorists write of our ever better understanding of the Standard Model and of what might lie beyond. Risky as it is to highlight only a couple of exciting subjects, it is merely meantto whet the appetite for further reading.

Stanford University hosted the XIX International Symposium on Lepton and Photon Interactions at High Energies on August 9 - 14, 1999, at the Law School on the Stanford University Campus, the site of the previous Symposia. This volume constitutes the proceedings of the Symposium.

This conference series reviews progress in understanding the physics of the 5th quark (beauty quark or bottom quark) and the properties of particles containing a b-quark. These quarks are produced at particle accelerators such as electron-positron accelerators or hadron colliders with the latter being the focus of the conference. One of the main issues in understanding the physics of the 5th quark is CP violation, a mechanism in particle physics that breaks the symmetry of nature between particles and antiparticles ultimately connected to the particle-antiparticle asymmetry of the universe. Topics include: recent results; CP violation; B production and spectroscopy; detectors, hardware, and computing; Vucb, Vub, and factorization; B lifetimes and mixing; rare decays; B trigger at future experiments; B physics at future hadron machines; the future of flavor.

These proceedings cover the latest results in Tevatron Collider Physics, LEP results, and results from other High Energy Physics Laboratories. The volume will consist of plenary and parallel contributions on the following subjects: Heavy Quark Physics, Physics Beyond the Standard Model, Astrophysics and Non-Accelerator Physics.

Stanford University hosted the XIX International Symposium on Lepton and Photon Interactions at High Energies on August 9 - 14, 1999, at the Law School on the Stanford University Campus, the site of the previous Symposia. This volume constitutes the proceedings of the Symposium.