Research on delinquent behavior has traditionally been a core emphasis of Nordic criminological research. Historically, Nordic cooperation in criminology began with the world's first ever internationally comparative survey of self-reported delinquency, the Nordic Draftee Research program, 1961-64. Youths of the five Nordic nations tend to manifest relatively similar prevalence levels of delinquent behavior, with a partial exception that Danish adolescents have above-average levels of substance use and property offending. During the 1990s, Danish, Finnish, and Swedish surveys revealed a consistent rise in the number of law-abiding youths, a trend explained by a coincidence of multiple social changes: diminishing cohort sizes, the rise of the surveillance society, increasingly conservative and anti-crime attitudes among youths, and changing routine activities, some of which may have resulted in crime-type displacement (from traditional theft to computer-related crime) instead of overall crime reduction. Reviewed articles in core journals reveal that focal concerns of Nordic delinquency researchers have been social problems-related research, the question of generality versus specialization of delinquency, longitudinal research in individual-level risk factors, methodological research, and research on the social causation of delinquency. (Published Abstract)