Measurements of the temperature- and concentration-dependent surface tensions of aqueous solutions of methanol, 1- and 2-propanol, 1- and 2-butanol, acetic, propionic, and butanoic acids, and acetone were used to determine the standard free energies, enthalpies, and entropies of adsorption from the vapor phase onto a water surface. The saturated surface coverage of all these species is approximately 10(14) molecules cm(-2). The standard enthalpies of adsorption are correlated to the enthalpies of solution, suggesting that these molecules are partially solvated in the adsorbed state. These results further suggest that atmospheric water droplets could be coated with an organic layer.