The monograph is devoted to the description of innovative investment models created by the authors recently and well tested in practice, and their application. Existing investment models are unable to correctly assess the efficiency of investments. This is due to both the lack of self-consistent models based on first principles and the inability of correctly assessing the discount rate. The innovative investment models created by the authors recently were modified for the conditions of real implementation of investment models (with frequent payments of income tax and interest on debt both at the end of periods and as advance payments, variable payments, etc.). The influence of these types of payments on the efficiency of investment projects is studied. The efficiency of an investment project is considered from two points of view: the owners of equity and debt, as well as only the equity. The latest versions of two main theories of capital structure (Brusov–Filatova–Orekhova (BFO) and Modigliani–Miller (MM)) are described, allowing to correctly assess the discount rate when assessing the efficiency of investment projects (long-term as well arbitrary duration). The practical application of the created investment models is described, as well as ratings of investment projects.