We develop a nonequilibrium theory to describe weak Coulomb blockade effects in open quantum dots. Working within the Bosonized description of electrons in the point contacts, we expose deficiencies in earlier applications of this method, and address them using a \(1/N\) expansion in the inverse number of channels. At leading order this yields the self-consistent potential for the charging interaction. Coulomb blockade effects arise as quantum corrections to transport at the next order. Our approach unifies the phase functional and Bosonization approaches to the problem, as well as providing a simple picture for the conductance corrections in terms of renormalization of the dot’s elastic-scattering matrix, which is obtained also by elementary perturbation theory. For the case of ideal contacts, a symmetry argument immediately allows us to conclude that interactions give no signature in the averaged conductance. Nonequilibrium applications to the pumped current in a quantum pump are worked out in detail.