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 {1 1 0} planes associated with the primary crack system {1 1 0} / 〈1 1 0〉. The normalized fracture toughness was used to calculate the directional fracture energy on the {0 0 1} plane and was consistent with a theoretical model based on calculating the number of broken bonds.