Dated arrest histories of a sample of prisoners released from state prisons in 1994, collected by the Bureau of Justice Statistics, were used to model re-offending trajectories and study their deflection. A semi-parametric method was used to develop plausible counterfactual trajectories and compare them with actual postrelease offending patterns. Analysis suggests that most individuals were either deterred from future offending (40 percent) or reverted back to projected offending patterns (56 percent) as a result of their incarceration. About 4 percent had a criminogenic effect.