NMR data can be analyzed independently or in combination with conventional logging data. When NMR data are interpreted independently, they can provide porosity and permeability as well as complete information on fluid types and fluid saturation in the invaded zone. Many models have been developed for the stand-alone analysis of NMR logging data; both the Time Domain Analysis (TDA) model and the Diffusion Analysis (DIFAN) model, for example, are well used. Another model called the Enhanced Diffusion Method (EDM) can be implemented during data acquisition and provides valuable information for viscous oil detection. Complete descriptions of these models and their applications are discussed in this chapter.