Although single crystal gallium arsenide (GaAs) is a technologically important semiconductor material, its mechanical behavior is poorly understood. In this study, the Vickers microindentation technique was leveraged with a quantitative fractographic approach to determine the fracture energy and toughness corresponding to various crystal planes. Cracks preferentially propagated along the {110} planes associated with the primary crack system {110} / 〈110〉. The normalized fracture toughness was used to calculate the directional fracture energy on the {001} plane and was consistent with a theoretical model based on calculating the number of broken bonds.