Recent discoveries of extrasolar planets and new direct evidence for protoplanetary disks around young stars have had a major impact on our understanding of star and planet formation. This book provides a thorough, up-to-date, and concise overview of the physical processes involved in the formation of stars and the disks around them which ultimately form planets. The book traces the story of star formation from the fragmentation of cold molecular gas clouds, through to the formation of protostars and rotating dusty disks and the subsequent accretion of material onto the central star. Throughout, state-of-the-art theoretical models are integrated with recent observations, and in this way important problems which remain to be solved are highlighted. This book provides graduate students and researchers with the first comprehensive account of the dynamical processes of star and protoplanetary disk formation.