Criminology has long asserted that its goal is to be a science. Criminologists make great efforts to use appropriate research methods and to adopt the newest methodological and statistical techniques to their studies of the causes of crime. Those new methods and statistical procedures themselves do not guarantee that what criminologists do is scientific. What criminologists have neglected in their effort to be recognized as a science is establishing the scientific basis of their core concept, crime. The criminal-law definition of crime that criminologists rely on is not scientific. These limitations to the criminal- law definition of crime, however, cannot be overcome by employing the latest methods for collecting data or the latest statistical procedures for analyzing crime data. As a result, the central dilemma that criminology faces in its effort to become a science is its need to critically assess its definition of crime and to understand why the legal definition of crime is not a proper basis for the scientific study of crime. Perhaps it is an impossible task to create a scientifically based definition of crime. If so, then the idea that criminology can be or is a scientific field of discovery must be assessed. Criminology must either revise its concept of crime to achieve the status of a science or revise its expectations about becoming a science. In all likelihood, we do not believe that the majority of criminologists will accept either of these options. More than likely, criminology will continue on the historical path it has travelled, constrained by the legal definition of crime, and will ignore the need to reconstruct its concept of crime.