The term “assessment of medical technologies” does not appear to have a unique meaning that always applies to its use. It seems wise, then, to state what will be meant by the term in this chapter. “Medical technology” is regarded here as including drugs, devices, procedures, (whether preventive, diagnostic, or therapeutic) that bear more or less directly on patients. Thus, an educational program for patients might be a technology, but a training program for dietitians would not. A surgical procedure or a prosthesis would; but a scale for assessing quality of life would not. “Assessment,” as used here, refers to a complex set of activities that comprise data acquisition, analysis, and interpretation concerning properties of medical technologies. Assessment tends to be comparative, either explicitly (as to a control group) or implicitly (as looking toward “usual experience”). In any case, the goal of assessment is to increase understanding of such properties of a medical technology as its applicability, convenience, efficacy, safety, effectiveness, cost, etc.