t Hooft conditions in supersymmetric dual theories

The matching of global anomalies of a supersymmetric gauge theory and its dual is seen to follow from similarities in their classical chiral rings. These similarities provide a formula for the dimension of the dual gauge group. As examples we derive ʹt Hooft consistency conditions for the duals of supersymmetric QCD and SU(N) theories with matter in the adjoint, and obtain the dimension of the dual groups.