Selective incapacitation involves the early identification of delinquents with a high probability for recidivism or violence and their incarceration to prevent their projected high volume of crimes. Collective incapacitation is the prolongation of imprisonment to prevent crimes that would otherwise be committed had release occurred earlier. An assessment of the validity of these incapacitation concepts must focus on factors that cause recidivism. The incapacitation concepts posit that recidivism is caused by factors in offenders themselves which remain constant (static theory). Another recidivism theory reasons that imprisonment is a significant factor in increasing the likelihood of recidivism (dynamic theory). These theories were tested with data from a 20-year study of 500 male juvenile offenders released from the prisons of Herford and Staumuhle (Northrine-Westphalia) between January 1 and October 17, 1960. Offenses used in the measurement of recidivism were recorded in the Federal convictions register. Data on corrections histories and socialization or psychological deficits were obtained over four 5-year investigative periods. The study concludes that incapacitation, rather than reducing recidivism, increases it. Thus, imprisoned offenders are at increased risk to continue their criminal careers with greater intensity after release. 2 figures, 8 notes, and 54 references