Following an introduction to the theory of microscopic bodies based on the fundamental atomic laws, this book contains a brief but self-contained discussion of thermodynamics and the classical kinetic theory of gases. An introduction to the modern theory of critical phenomena is featured. This edition contains coverage of recent major advances and important applications, such as superfluids and the Quantum Hall Effect. A large part of the text is devoted to selected applications of statistical mechanics and its value as an illustration of calculating techniques.