The papers in this volume examine the recent revolutionary discoveries in cosmology and astronomy, and their theoretical interpretation. The observational evidence for an accelerating universe, and an earlier decelerating phase, is brought up to date with the newest results for the most distant and oldest Type Ia supernovae. The data from the WMAP satellite provide, for the first time, true precision cosmology: reliable results for the age of the universe, its geometry, its evolution over the past 13.7 billion years, and many other features, including the proportions of ordinary matter, dark matter, and dark energy. Other papers in this volume describe the information obtained with 21st century astronomical techniques, including gravitational lensing, studies across the electromagnetic spectrum with ground-based and NASA observatories, and surveys of millions of galaxies. The results are interpreted by leading theorists using both accepted and exotic theories, including inflation and superstring theory.