Oscillations in both the intensity and width of reflection high‐energy electron diffraction beams that are measured during the MBE growth of GaAs are observed to depend upon most growth parameters. The envelope of the intensity oscillations, for example, depends upon the flux ratios, the substrate temperature, the sample misorientation, the scattering geometry, the sample flatness, and the flux uniformity. To separate these dependencies we have made RHEED measurements on small, exceedingly flat, near singular samples. The angular profiles of the specular beam were measured during the first two periods of oscillations. These data were analyzed in terms of the two‐level diffraction calculation of Lent and Cohen. The measured profiles are in excellent agreement with that calculation. For oscillations with a 26‐s period, moderate changes in the substrate temperature and As flux can cause significant changes in the pair correlation length on the surface.