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We consider configuration mixing for the nonstrange positive parity excited baryons in the [56 ′ , 0 + ], [56, 2 + ], [70, 0 + ] and [70, 2 + ] quark model SU (6)×O(3) multiplets contained in the N = 2 band. Starting from the effective mass operator for these states we show by an explicit calculation that in the large N c limit they fall into six towers of degenerate states labeled by K = 0, 1, 1 ′ , 2, 2 ′ , 3.We find that the mixing of the quark model states is much simpler than what is naively expected.To leading order in N c only states carrying the same K label can mix, which implies that for the spin-flavor states we started with configuration mixing can be parameterized by just two constants, µ K=1 and µ K=2 .

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