Cement-based waste forms are one of the most widely used waste disposal options, yet definitive knowledge of the fate of the waste species inside the waste form is lacking. A fundamental understanding of the chemistry and microstructure of the waste forms would lead to a better understanding of the mass transfer of the waste species, more confidence in predicting and extrapolating waste-form performance, and improved design of waste forms. Better and cheaper leach tests would lead to quicker and more cost-effective screening of waste-form alternatives, cement-based and otherwise. In addition, assessment of durability may be important to predicting waste-form performance in the field over periods of decades and centuries.