Andrews and Bonta identified the following criminogenic needs as important to reducing offending: substance use, antisocial cognition, antisocial associates, family and marital relations, employment, and leisure and recreational activities. This study examines dynamic criminogenic need changes across a 12-month period and identifies which need changes are the best predictors of criminal offending and illicit drug use among a sample of drug-involved probationers who participated in an intervention (N = 251). Probationers had significant changes in several need areas, and treatment participation moderated some changes. Probationers who had reductions in criminally involved family members they associate with, improved work performance, and decreased alcohol use had the greatest reductions in offending. Those who increased time spent engaged in leisure and recreational activities were less likely to self-report subsequent drug use. These findings suggest that certain dynamic need changes may be more important than others, and designing interventions to impact these needs might improve outcomes.