Book excerpt: The Variation Method in Quantum Chemistry is generally a description of the basic theorems and points of view of the method. Applications of these theorems are also presented through several variational procedures and concrete examples. The book contains nine concise chapters wherein the first two ones tackle the general concept of the variation method and its applications. Some chapters deal with other theorems such as the Generealized Brillouin and Hellmann-Feynman Theorems. Also covered in the discussion is the relation of the Perturbation Theory and the Variation Method. This book will be of great help to students and researchers studying quantum chemistry.