Suppression and restoration of superconductivity in PrBa2Cu3O7

I review the principal experimental findings about superconductivity, suppression thereof, and related properties of RE_{1-x}Pr_xBa_2Cu3O7 in a decision-tree manner, eliminating the models substantially incompatible with established experimental facts, eventually focussing on the pf\sigma hybridization models and listing on a verbal level the interpretations of the existing experiments as they emerge from such models.