Kinetic Theory in the Expanding Universe is a self-contained exposition of the applications of kinetic theory to basic problems in modern cosmology, such as the role of stable and unstable massive neutrinos and the theory of cosmological helium production. There has been rapid development of the theory of the origin and evolution of the universe in recent years, stimulated, in large part, by new observations and theories in astrophysics and particle physics. Bernstein takes a different approach and studies what can be concluded from the application of kinetic theory, and in particular the Boltzmann equation and its solutions, to cosmological problems. He begins with a brief survey of the necessary relativity, cosmodynamics, and kinetic theory, before going on to discuss specific problems, such as the role of stable and unstable massive neutrinos, electron-positron annihilation and the theory of cosomological helium production. The focus is in obtaining both a theoretical understanding and concrete numerical results.