Absorption due to boron vibrational modes in GaP has been measured. At 20 °K gap modes of ¹¹B and ¹⁰B occur at 284·2 and 293·8 cm^-1, local modes occur at 571·0 and 593·6 cm^-1 and local +gap modes occur at 849·0 and 882·4 cm^-1. An approximate calculation of the boron vibrational mode frequencies gives reasonable agreement with experiment.