Three different thermal analysis techniques (DSC, and hot-stage optical microscopy equipped with a photodiode to measure light depolarization or a video system to measure spherulitic growth) were used to study polymer crystallization. The fold surface free energy (sigma(e)) values from different analytical methods on five polymers are compared. The overall crystallization data always yield sigma(e) values 15-50% higher than those obtained from the more direct method of measuring growth rate.