This concise introduction to the key concepts and tools of modern statistical mechanics is self-contained. Combining analytical and numerical techniques, it also covers advanced topics such as non-relativistic quantum field theory. After introducing classical analytical techniques, the authors present important numerical methods and a diverse range of applications. Quantum statistical mechanics is then analyzed and applied to topics in astrophysics and cosmology. Combining the authors' many years' experience of teaching courses in this area, this textbook is ideal for advanced students in physics, chemistry and mathematics.