Book excerpt: The concepts of appropriate and necessary care are fundamental to the creation of an efficient and equitable health-care delivery system. Evidence of inappropriate overuse and underuse of procedures has been documented even in health systems characterised by the absence of global budgets, capitation, utilisation review or the pressure of requiring a second opinion. Health systems should function in such a way that inappropriate care is progressively reduced, while appropriate and especially necessary care are maintained or increased. The ability to determine and identify which care is overused and which is underused is essential to this functioning. To this end, the "RAND/UCLA Appropriateness Method" (here given the acronym RAM) was developed by RAND and UCLA in the 198Os. It has been further developed and refined in North America and, increasingly, in Europe.