Collisional transport theory is of central importance to modern plasma physics. This book provides a self-contained treatment of the subject, starting from elementary concepts and developing the theory through to the research frontier. Basic tools of kinetic plasma theory, such as the drift kinetic equation and the Coulomb collision operator, are derived, and are then used to calculate classical and neoclassical transport occurring in high-temperature plasmas. Important phenomena such as neo-classical diffusion, bootstrap current, and plasma rotation are carefully explained. Students, theoreticians and experimentalists in both fusion and space plasma physics will benefit from this book, which emerged from a graduate student level course taught at MIT.