Solidification/stabilization (S/S) technology is widely used in the treatment of hazardous waste and contaminated soil in the U.S. In a project sponsored by the U.S. Navy and the U.S. Environmental Protection Agency (U.S. EPA), treatability test data were compiled into a data base listing contaminant concentration and matrix, binder type and ratio, and effects of S/S treatment on 18 metals. Preliminary analysis showed that S/S treatment achieved substantial reduction in laboratory-measured leachability in the majority of cases involving silver, cadmium, lead and mercury; however, selenium, arsenic, chromium and barium were less readily treatable. Numerical correlations between waste or binder properties and degree of immobilization were not readily apparent, possibly because of gaps in available data. In this study, a subset of the data base was selected and analyzed graphically to elucidate general relationships between waste and binder properties and the effectiveness of S/S treatment. Relationships were examined between the degree of immobilization and such factors as leachable metal concentration in the raw waste, extraction test procedure, binder, binder-to-waste ratio and extract pH. Leachate pH was the best indicator of lead leachability, with very strong trends in a single study and noticeable trends in the larger data base. Overall, however, the existing data do not indicate how to predict S/S performance without conducting treatability tests on new materials being considered for treatment.