Hydrogen neutralizes both donors and acceptors in GaP by a mechanism that is independent of the site of the impurity in the lattice, but is dependent on the identity of the impurity. Hydrogen also passivates an isoelectronic trap nitrogen, a phenomenon first encountered here in GaP. We propose a simple model for the NH binding based on a polarized N−H+bond. This model accounts for the relative passivation of a series of NN pairs, where the passivation depends critically on the NN separation distance. Our results also support the recently revised correlation of spectral lines with NN pairs of varying separations.