This discussion has highlighted only some of the areas of behavioral pharmacology research with PCP, focusing largely on studies in our laboratories. Some of the areas touched upon lightly have been much more extensively investigated (e.g., PCP-like properties of psychotomimetic opioids). Some areas, such as the search for a PCP antagonist, have been studied with relatively little success so far. Two other areas, among many that are worthy of mention, are the extensive series of studies of the effects of PCP on complex learning procedures, starting with the studies by Moerschbaecher and Thompson (1980a, Moerschbaecher and Thompson 1980b), and an elegant series of studies on the determinants of oral PCP self-administration, beginning with the study by Carroll and Meisch (1980). Much progress has been made on the clinical implications of behavioral research with PCP, and we are in a much better position to respond effectively to this public health problem than we were when it emerged, only a little over 10 years ago. The impetus behind PCP research has come from two directions--from the emergence of PCP as a drug of abuse with the pressing practical questions raised by this epidemic, and from the potential that PCP research has for a fuller understanding of the brain and behavior. Although this discussion has focused on the former, progress toward the latter goal has been equally, if not more, substantial, and may have long-term health implications far beyond those presented by problems of PCP abuse.