The analysis of the effect of the structural disorder on second order phase transitions leads to the following two questions. First, do the critical exponents of a "pure" magnetic system change at the dilution of it by nonmagnetic impurities? Second, if they do change, are these new critical exponents universal, i.e., independent of the concentration of structural effects up to the percolation threshold? The answer to the first question was given in [1]. It was shown that the critical exponents for the systems with quenched structural defects differ from those characteristic of similar systems without defects if the critical exponent for the specific heat in the pure system is positive. This criterion is met only for three dimensional systems with the critical behavior described by the Ising model. The critical behavior of dilute Ising-type magnetic systems was studied in [2-9] using the renormalization-group techniques, numerical Monte Carlo simulations, and experimental methods. Currently, we have a positive answer to the question concerning the existence of the novel universality class for dilute Ising-type magnetic systems. However, it is still not quite clear whether the asymptotic values of the critical exponents are independent of the degree of dilution in the system, how the crossover effects can change these values, and whether two or more regimes of the critical behavior for weakly and strongly disordered systems can exist. These questions are still open and are actively discussed.