Four major methods for the thermal analysis of proteins are reviewed. Thermogravimetric analysis (TGA) is commonly used for moisture content measurements in raw materials and lyophilized protein products. Differential scanning calorimetry (DSC) can detect and quantitate changes in the transition temperature and enthalpy due to formulation variables such as pH, ionic strength, and stabilizers. DSC is also used to detect the glass transition temperature T(g) in protein solutions and lyophilized products. The determination of T(g) is necessary in defining a freeze-drying cycle and storage temperature for the lyophilized products. Thermomechanical analysis (TMA) is used to detect T(g) and is more sensitive than DSC. Electrical resistance measurement has been used to detect eutectic temperature and thermal expansion events but its application in detecting T(g) requires further investigation.