Pulsed and CW measurements have been made of the nuclear magnetic resonances of 69Ga, 71Ga, and 31P in polycrystalline GaP. The resonance line shapes are approximately Gaussian with line widths ~ 10 per cent greater than the calculated dipolar widths. The origin of the additional broadening is discussed and compared with line broadening observed in other III–V semiconductors. Positive frequency shifts of the gallium resonances in GaP relative to GaCl 3 of Δ v ( 69Ga) = 0.65 ± 0.07 kc s and Δν ( 71Ga) = 0·95 ± 0·07 kc s are observed. The spin-lattice relaxation times T 1 have been measured using pulsed n.m.r. techniques. The phosphorus T 1 temperature independent between 77–462°K and is attributed to spin-diffusion limited relaxation via paramagnetic impurities. The gallium relaxation arises from time-dependent quadrupole interactions and in the range 77–700°K can be fitted to Van Kranendonk's temperature dependence for a two-phonon relaxation process using a Debye temperature Θ ~ 400°K. Quadrupolar relaxation in strongly covalently bonded crystals is discussed briefly.