We suggest that annealing GaAs samples at high temperatures encourages the relatively rapid in‐diffusion of divacancies which either are acceptors themselves or quickly dissociate into acceptors. Rapid quenching to room temperature freezes in these defects and results in altered electrical properties for the samples. A simple model, fit to some sparse existing data, yields a 950 °C estimate of (3–5)×10−7cm2/s for the diffusivity of the divacancy. When combined with other existing data, obtained at lower temperatures, on the in‐diffusion of a defect with a level atEc‐0.23 eV and tentatively identified as the divacancy, we find the diffusivity of the divacancy to be given by (3×10−3)exp(−0.94 eV/kT) cm2/s over the temperature range 250–950 °C.