A composition comprises a solid dispersion comprising a low-solubility drug and at least one polymer. At least a major portion of the drug in the dispersion is amorphous. The polymer has a glass transition temperature of at least 100° C. measured at a relative humidity of fifty percent. Another aspect of the invention comprises the same composition except that the dispersion has a glass transition temperature of at least 50° C. at a relative humidity of fifty percent. In another aspect of the invention, a composition comprises a solid dispersion comprising a low-solubility drug and a stabilizing polymer. At least a major portion of the drug in the dispersion is amorphous. The composition also includes a concentration-enhancing polymer that increases the concentration of the drug in a use environment. The stabilizing polymer has a glass transition temperature that is greater than the glass transition temperature of the concentration-enhancing polymer at a relative humidity of 50%.