This chapter offers an in-depth theoretical analysis of the optical properties of vanadium dioxide (VO2), a material known for its metal–insulator transition. Relying exclusively on classical models—the Drude model for free electrons, the Lorentz model for bound electrons, and their combination in the Drude-Lorentz model—we describe the analytic expressions of the complex dielectric function as well as the resulting optical quantities, such as the refractive index, the absorption coefficient, etc. reflectivity and transmittivity. This study provides a better understanding of the fundamental optical behavior of VO2 based on established physical principles, without the need for numerical or experimental calculations.