This study examines how religiosity, specifically, church attendance, prior to admission into an addictions treatment facility (Teen Challenge) is related to the treatment outcomes of completing the program and the participants' length of stay in treatment. Additionally, the study investigates how other factors such as marital status, ethnicity, alcohol and drug use, and level of education may be related to retention rates and treatment outcomes. Using archival data of 388 enrollees in a Teen Challenge program in southern United States, the results show that religiosity prior to treatment admission is significantly related to program completion. However, the second outcome variable, length of time in treatment was not significantly related to religiosity. The findings also reveal that education was positively related to length of treatment, but not program outcomes. While more study is needed to understand the relationship between religiosity and addiction program completion, this study confirms a positive relationship between church attendance prior to treatment and program completion.