Abstract
A generalization of charge symmetry, called "flavor symmetry," is applied to the constituent-quark model to relate the sum of magnetic moments of mirror pairs of baryons to quark moments. With only the added assumption that the ratio of u- and d-quark moments is - 2, the general sum rule, μ(Σ+)+μ(Ξ0)μ(Σ)μ(Ξ)=2.640 nuclear magnetons, is established. Relativistic corrections are estimated to be less than 4%. Larger deviations from the sum rule would indicate electromagnetic annihilation of highly correlated pairs in the quark sea.