First, some of the computational methods that are used and have been developed to model the structure of individual nanoparticles, systems containing nanoparticles, and nanoparticle interactions with their surroundings are discussed by describing both their theoretical basis and their advantages and disadvantages. This is followed by the presentation of one computer simulation technique: coarse-grain Monte Carlo simulation. As a prototypical system, the problem of the interaction of polyelectrolyte chains with oppositely charged nanoparticles is considered, different situations are discussed, and an attempt is made to isolate the potential influence of experimental parameters.