With nearly 8.2% of Americans experiencing substance use disorders (SUDs), a need exists for effective SUD treatment and for strategies to assist treatment participants to complete treatment programs (Chandler, Fletcher, & Volkow, 2009). The purpose of the current research is to contribute to an emerging knowledge base about treatment readiness and its utility for predicting substance use treatment process performance measures. The study examines the relative salience of treatment readiness as a predictor of treatment engagement. Data are derived from adult cases included in the 2012 Global Appraisal of Individual Needs-Intake data set (n = 5,443). Binary logistic regression was used to identify if treatment readiness predicts substance use treatment engagement. The findings of this study do not provide support for treatment readiness significantly predicting substance use treatment engagement. Further research is needed to better understand treatment engagement.