Hybrid Methods of Molecular Modeling is a self-contained advanced review offering step by step derivation of the consistent theoretical picture of hybrid modeling methods and the thorough analysis of the concepts and current practical methods of hybrid modeling based on this theory. Hybrid Methods of Molecular Modeling presents its material in a sequential way paying attention both to the physical soundness of the approximations used and to the mathematical rigor necessary for practical developing of the robust modeling code. Historical remarks are given when it is necessary to put the current presentation in a more general context and to establish relation with other areas of computational chemistry. The reader should have experience with basic concepts of computational chemistry and/or molecular modeling. Basic knowledge of operators, wave functions, electron densities is necessary.