Considerable attention has been given to sulfate-induced heave in soils stabilized with calcium-based stabilizers over the past two decades. Empirical evidence has supported threshold values of water-soluble sulfates that are used as guidelines to define the risk of distress. This study uses two approaches to evaluate these sulfate threshold values as well as to compare the sensitivity of soils with different mineralogies to sulfate-induced damage. Five soils, each belonging to a different soil series and with significantly different chemistries and mineralogies, are evaluated. Differential scanning calorimeter and stoichiometric mass balance calculations based on a thermodynamics-based phase diagram approach are used to evaluate the influence of mineralogy on soil behavior. The variation in sensitivity of different soils to ettringite formation was substantiated and was found to be dependent on reactive clay content in the soil. Although the sensitivity of soils to ettringite formation was observed to change with the availability of reactive clay fractions, no definitive relationship was established between clay content and weight percentage of ettringite formed. The empirical threshold of about 3,000 ppm is generally substantiated as is the efficacy of the concept of extended mellowing periods with homogeneous mixing while adding as much mixing water as possible. Finally, a general agreement between the mass balance predictive approach and the direct measurement by using the differential scanning calorimeter was established.