Amorphous pharmaceutical materials have received considerable attention in recent years because of their unique handling, processing and stability characteristics. A key question that arises with such materials is "what is the molecular mobility of the material, and how does this influence its performance?". In this manuscript, the use of differential scanning calorimetry (DSC) to characterize the molecular mobility of amorphous pharmaceutical materials is reviewed, and several applications of the data for the qualitative and quantitative prediction of their performance are presented.