Objective: The failure of offenders to complete psychological treatment can pose significant concerns, including increased risk for recidivism. Although a large literature identifying predictors of offender treatment attrition has accumulated, there has yet to be a comprehensive quantitative review. Method: A meta-analysis of the offender treatment literature was conducted to identify predictors of offender treatment attrition and examine its relationship to recidivism. The review covered 114 studies representing 41,438 offenders. Sex offender and domestic violence programs were also examined separately given their large independent literatures. Results: The overall attrition rate was 27.1% across all programs ( k = 96), 27.6% from sex offender programs ( k = 34), and 37.8% from domestic violence programs ( k = 35). Rates increased when preprogram attrition was considered. Significant predictors included demographic characteristics (e.g., age, r w = −.10), criminal history and personality variables (e.g., prior offenses, r w = .14; antisocial personality, r w = .14), psychological concerns (e.g., intelligence, r w = −.14), risk assessment measures (e.g., Statistical Information on Recidivism scale, r w =.18), and treatment-related attitudes and behaviors (e.g., motivation, r w = −.13). Results indicated that treatment noncompleters were higher risk offenders and attrition from all programs significantly predicted several recidivism outcomes ranging from r w = .08 to .23. Conclusions: The clients who stand to benefit the most from treatment (i.e., high-risk, high-needs) are the least likely to complete it. Offender treatment attrition can be managed and clients can be retained through an awareness of, and attention to, key predictors of attrition and adherence to responsivity considerations.