Interfaces are considered as one the crucial factors determining the properties of the polymer/particulate nanocomposites. Often, a prerequisite for obtaining the desired properties in the nanocomposites is the proper surface modification of the nanoparticles. This chapter presents the state of the art in methods and strategies for engineering the nanoparticles surfaces, including the utilization of silane coupling agents, titanate coupling agents, phosphonic acid/phosphonates, dopamine, polymer coating and inorganic coating. For each strategy, case studies are provided for illustrating the importance of the nanoparticle surface modification in determining the electrical properties of the polymer nanocomposites.