We report a study on the N incorporation in GaP grown by gas‐source molecular beam epitaxy using a N radical beam source. Contrary to theoretical predictions under thermoequilibrium conditions, GaNP with N concentration as high as 16% has been obtained without showing any phase separation, but increasing the growth temperature will result in a decrease of N incorporation. These results indicate that using nonequilibrium growth techniques can achieve GaNP alloys with a N concentration far greater than the thermal equilibrium solubility limit. Optical absorption measurements reveal that although the band gap energy of GaNxP1−x decreases with increasing N concentration, it is still positive for x up to 16%, indicating that the material is not a semimetal but a semiconductor, contrary to theoretical predictions based on the Van Vechten’s quantum dielectric model.