We have investigated the effect of several surfactants on the homoepitaxial growth of Ag(111) by X-ray reflectivity experiments. Recently, we found that submonolayer amounts of Sb induce layer-by-layer growth of Ag on Ag(111). Now we have varied the amount of Sb and also used In, Pt and O2 as surfactant. We show that Sb is not unique in inducing two-dimensional growth in Ag(111) homoepitaxy: In and Pt have the same effect. For O2 the sticking coefficient to Ag(111) is too low to affect the growth significantly. At the lowest growth temperatures (< 170 K), only Sb induces layer-by-layer growth.