Economists' contributions to criminal justice research can be divided into three main areas of theory, technique, and substantive expertise. Economists' work on perceptual deterrence, with its emphasis on the centrality of time discounting, has already been incorporated into criminological research. There has been a much more mixed record in taking up economic approaches to criminal justice theory: early work on prosecutors has been neglected, whereas the newer are of outcome analysis, based on maximizing behavior by criminal justice actors, has influenced criminological work on discrimination. There is a mixed record with respect to technique. Econometrics methods, particularly James Heckman's approaches to selection problems, have been influential but are often mishandled. Cost-benefit analysis, though much sought after by policymakers, has not entered mainstream criminology. One substantive area in which economists have substantive expertise concerns illegal markets, especially drug markets. The research by economists has produced important findings on intervention outcomes such as price and quantity. Criminology can benefit from collaboration with economists by need not worry that the economists will soon take over. (Published abstract)