The increasing use of solidification/stabilization (S/S) technologies in the United States, especially for remediation of sites under the Superfund program, has raised several questions about the overall appropriateness of S/S. For many types of hazardous waste, notably for heavy metals, S/S usually gives excellent results for long-term immobilization, as measured by existing physical and chemical protocols. However, results of several studies, as well as data from remediation of several Superfund sites, have raised concerns about whether S/S is a valid technology for treating organic-bearing wastes. Furthermore, studies also provide evidence that tests other than the regulatory extraction tests (for example, toxicity characteristic leaching procedure (TCLP)) will be required to evaluate the effectiveness of S/S, especially when applied to organic wastes. Suggestions are offered for improving treatability studies used for evaluating S/S applied to selected metals. Approaches are also provided for determining the appropriateness of S/S applied to organic contaminants. The paper will focus on evaluating chemical leaching behavior as a measure of S/S effectiveness. A decision tree is presented for determining the suitability of S/S treatment for wastes containing organic contaminants, which can be more difficult than metals to immobilize.