We have measured the adsorption of poly(dimethylsiloxane) from solutions of toluene (good solvent) and 2-butanone (Theta solvent) to the solution/vapor interface at 20.0 degrees C. The adsorption was studied using surface tensiometry and X-ray evanescent wave induced fluorescence (XEWIF). In the XEWIF method, the atomic fluorescence of Silicon, contained in the polymer, was measured as a function of an X-ray excitation depth beneath the liquid/vapor surface. Cu K alpha(1) X-rays from a conventional tube source were used to excite the fluorescence in a spectrometer of our design. The data were interpreted by fitting model step adsorption profiles and then calculating the surface adsorption excesses as a function of molecular weight and concentration. Two polymer samples were studied, with weight average molecular weights of 38.9 x 10(3) and 631 x 10(3) g/mol and M(w)/M(n) equal to 2.84 and 1.73, respectively. No strong molecular weight or concentration dependencies were observed. Although the addition of polymer reduced the surface tension more in toluene solution than in 2-butanone, a greater surface excess was observed in the 2-butanone solutions. The comparison of the polymer adsorption in the two solutions allows us to discuss the relative influence of the surface and the bulk solution quality in determining the surface excess.