The Langmuir compression isotherms of p-dodecanoylcalix[4]arene have been studied on subphases containing varying concentrations of group IA salts. The effect of anions on the stability of the monolayers shows that, for acetate and bicarbonate, there is a large increase in collapse pressure, when sodium is the countercation. In the case of cation effects, rubidium chloride shows a large stabilization of the monolayer.