This methodological study assesses the impact of available street time and mortality on the estimation of recidivism. Using survival analysis techniques to derive estimates of reoffending, the study compares adjusted and unadjusted rates and assesses how these rates vary for different offender populations and over different follow-up periods. In contrast to some previous studies, it finds that adjusting for time spent in custody and mortality makes little difference to the two-year recidivism rates of large offender populations.