This second edition of one of the most important and best selling textbooks in statistical physics, is a graduate level text suitable for students in physics, chemistry, and materials science. Highlights of the book include a discussion of strongly interacting condensed matter systems with a thorough treatment of mean field and Landau theories of phase transitions. Discussions of the Potts model and the asymmetric exclusion process have been added. Along with traditional approaches to the subject such as the virial expansion and integral equations, newer theories such as perturbation theory and density functional theories are introduced. The modern theory of phase transitions occupies a central place in this book. A separate, largely rewritten, chapter is devoted to the renormalization group approach to critical phenomena, with detailed discussion of the basic concepts of this important technique and examples of both exact and approximate calculations given. The development of the basic tools is completed in an expanded chapter on computer simulations in which both Monte Carlo and molecular dynamics techniques are introduced.