Comparing risks of recidivism among gang and non-gang members on probation in Illinois is the focus of this article. Addressing differences in demographic and socioeconomic conditions, conviction offenses, substance abuse and criminal histories, and probation conditions and outcomes, the authors argue that gang members and non-gang members demonstrate different rates of recidivism. Analyzing data on over 3,300 adult probationers in Illinois collected through the 2000 Illinois Probation Outcome Study, this report argues that an estimated 6 percent of adults discharged from probation in 2000 were identified as gang members. Focusing on differences between the characteristics of Illinois gang members and non-gang members on probation, the authors report that gang members on probation tend to be never-married males who are younger in age, members of racial minorities, and who are unlikely to have completed high school or been employed at the time of sentencing. Furthermore, gang members on probation differ from non-gang members on probation in that they are less likely to have parented a child and are more likely to have a history of illegal drug use and abuse. Nearly 80 percent of gang members were on probation for committing felony-level offenses, and 40 percent of gang members were ordered by the court or referred by their probation officer to some type of substance abuse treatment program. After taking all differences between gang member and non-gang members into consideration and conducting a multivariate analysis on recidivism rates, the authors found that gang membership was the most influential factor in predicting Illinois probationer recidivism, suggesting that gang members on probation warrant specialized supervision and/or increased surveillance.