Convection is ubiquitous throughout the Universe, and during the last three decades it has become the largest factor of uncertainty in theoretical models of stars and in the interpretation of observations on the basis of such models. Recently, numerical simulations of convection have dramatically improved in their potential to take into account both the large scale properties of the flow itself and the microphysical properties of the fluid. Observations have become accurate enough to provide stringent tests for both numerical simulations and models of convection. IAU S239 was held to further understanding of convection, bringing together leading researchers in solar and stellar physics, the physics of planets, and of accretion disks. With reviews, research contributions, and detailed recordings of plenary discussions, this book is a valuable resource for professional astronomers and graduate students interested in the interdisciplinary study of one of the key physical processes in astrophysics.