The growth of Au on the Co decorated Au(111) surface has been studied by scanning tunneling microscopy. The decoration causes an increased sticking probability of the Au atoms to the Co covered elbows of the herringbone reconstruction until they are totally covered with Au. It is concluded that the attraction of the Co islands is strong enough to prevent the Au atoms from diffusing into subsurface layers (random growth mode) at room temperature, eventhough the Au layer is also far from growing in a layer-by-layer growth mode. The decoration of the substrate steps with Co islands enables the observation of the detailed changes in the morphology of the growing Au steps. © 1992.