The Finnish educational system streams students to academic or vocational tracks at the transition to upper secondary school. Organized as specialized training programs, vocational schools in Finland are highly segregated by gender and tend to attract significant concentrations of poorly motivated students with behavioral problems. Drawing on differential association theory, we hypothesize that these settings facilitate criminal involvement. Evidence from longitudinal data suggests that participation in vocational education is criminogenic for males but not females. Moreover, supporting the cumulative disadvantage hypothesis, participation in the vocational track mediates the association between low academic performance and the risk of criminal conviction. These findings raise concerns about a system of tracking prevalent in many European countries.