The delta solubility parameters of three families of polymers have been determined by two calculation methods suggested by Small and Hoy. Hansen’s model has also been used to assess delta and its components delta(d0), delta(p0), and delta(h0), so as to obtain more information on the intensity of the forces between the chain segments. Knowing the microstructure, the tacticity, and the thermal behavior of the copolymers has made it possible to explain both the different values of delta and the progression of solubility areas. Using Teas’ method has made it possible to visualize on the same map the influence of the forces of interaction. This representation shows that the presence of the vinylidene cyanide unit in styrenic chains implies an increase of delta(p) and a decrease Of delta(d), whereas delta(h) remains roughly constant for the corresponding homopolymer.