This book introduces an approach to protein folding from the point of view of kinetic theory. There is an abundance of data on protein folding, but few proposals are available on the mechanism driving the process. Here, presented for the first time, are suggestion on possible research directions, as developed by the author in collaboration with C. C. Lin. The first half of this invaluable book contains a concise but relatively complete review of relevant topics in statistical mechanics and kinetic theory. It includes standard topics such as thermodynamics, the Maxwell-Boltzmann distribution, and ensemble theory. Special discussions include the dynamics of phase transitions, and Brownian motion as an illustration of stochastic processes. The second half develops topics in molecular biology and protein structure, with a view to discovering mechanisms underlying protein folding. Attention is focused on the energy flow through the protein in its folded state. A mathematical model, based on the Brownian motion of coupled harmonic oscillators, is worked out in the appendix.