The present invention is a modulated differential thermal analysis technique for determining the composition, phase, structure, identification, or other properties of a material that undergoes a transition as function of temperature or other driving variable. As applied to differential scanning calorimetric analysis (DSC), the preferred embodiment comprises (1) heating a sample of the material with a linear temperature ramp that is modulated with a sinusoidal heating rate oscillation; (2) simultaneously heating a reference at the same linear temperature ramp; (3) measuring the differential temperature of the sample and reference; and (4) deconvoluting the resultant heat flow signal into rapidly and non-rapidly reversible components.