The room‐temperature lattice parameter of GaAs doped with Zn, Cd, Te, and Se has been measured with a precision of ±3 parts in 105using an x‐ray powder diffraction technique. Electrical measurements and microscopic examination of samples were used to qualify the measured lattice parameters and allow limits of the solute lattice dilation coefficient (&bgr;) to be calculated. For Zn in GaAs, &bgr;[equal to or less-than]1.2×10−25cm3/atom, for Cd in GaAs, &bgr;[equal to or less-than]1.1×10−24cm3/atom; for Se, &bgr;>1.3×10−24cm3/atom; and for Te, &bgr; >1.7×10−24cm3/atom. Limits of the stresses that could be generated at the onset of the diffusion of Zn, Cd, Te, or Se into GaAs are derived from these &bgr; values. It appears likely that these stresses will be sufficient to cause plastic flow and the generation of large numbers of dislocations for diffusion of any of these elements into GaAs under conditions of high diffusant surface concentration and high temperature. Preliminary experiments show that the diffusion of zinc into GaAs at 1100°C can generate a high dislocation density in the diffused layer.