The adsorption of Cd on Ge(111) was studied with combined RHEED‐MB techniques. The reciprocal lattice of the interface was mapped as a function of absolute adatom density. For low coverages, of the order of 10−3monolayers, the Cd adatoms clustered to form islands which were either static with random orientation with respect to the substrate or mobile ’’spinners’’. At a density of &sgr;=3.2×1014/cm2the islands took on substrate symmetry and formed an incommensurate overlayer having the structure of the basal plane of hcp Cd. The observations are discussed in terms of dangling‐bond densities and the uncertainties in the absolute density determination described.