Drivers under the influence of alcohol cause nearly one third of all fatal motor vehicle accidents. Ambulatory outpatient alcohol abuse treatment has been clinically shown to increase abstinence, which could decrease the chance of subsequent DWI offences. A barrier to successful completion is extended waiting periods prior to treatment engagement. The theory of patient waiting supports the longer a patient waits to begin treatment the lower the likelihood of successful completion. By exploring the impact of waiting times on DWI court mandated clients, referral courts and treatment facilities can work together to create a successful completion strategy for offenders. The research question focused on if days waiting can predict successful outpatient treatment completion in court mandated adults. The TEDS-D archival data set was used, consisting of data collected between 2006-€”2011 from federally funded substance abuse treatment centers throughout the USA. The variables time awaiting treatment, treatment level, gender, race, employment status, and age were used as controls. A logistic regression using a random sample of 4,947 participants determined days waiting was significant but weak in nature. The variables of employment status and age are stronger predictors of treatment completion. An interaction effect analysis of days waiting and age results in clients over 45 years old being significantly impacted by days waiting while younger clients are not. Court and treatment agencies can use this information to give priority intake appointments to older clients to increase chances of treatment completion.