Stellingwerf's one–zone model is a simple and useful tool for reproducing the main observed pulsational characteristics of RR Lyrae and high amplitude δScuti stars, in particular their light and color curves (Stellingwerf et al., 1987, Ap.J.313, L75; Antonello, 1990, Astr. Ap.230, 127). In the present poster we show in better detail a comparison of the observed amplitudes of the light curve at various wavelengths with those predicted by the one–zone model; a preliminary result on this subject was reported in the short note by Grieco and Antonello (1990, in Confrontation between Stellar Pulsation and Evolution p. 101). As in the previous applications, here we use the published grids of atmospheric models (Kurucz, 1979, Ap.J.Suppl. 40, 1) and we do not consider possible shock effects.