The authors state that criminal behavior, like every form of human behavior, has to be studied from three viewpoints: the biological, the psychological and the sociological. They call an approach which considers these three aspects 'a field-theoretical approach'.

The paper quotes a classification of criminals which has been worked out in the Menninger Clinic and which seems to be clear and useful. The authors give some short case histories in order to illustrate the complex nature of criminality. They point out the importance of a knowledge of the social situation for the understanding of crime although a knowledge of the social situation alone is not sufficient. The case history of a juvenile delinquent from a very respectable middle-class family, who attempted to rape an eleven-year-old girl, shows the limits of the sociological viewpoint. This case could not be understood without careful psychological, that is to say, psychoanalytic investigation.