High attrition continues to be an important issue for substance abuse treatment providers. This study examined factors contributing to treatment entry and dropout after referral from centralized assessment. Univariate analysis showed that individuals with a shorter wait after assessment were more likely to attend an initial treatment appointment, while those who reported a history of physical or sexual abuse or were on probation were significantly more likely to drop out of treatment early. Multivariate analysis revealed, first, that persons with a comorbid psychiatric diagnosis and those referred to outpatient rather than residential care were less likely to enter treatment; and, second, that persons on probation and with a history of physical or sexual abuse were more likely to be early treatment dropouts. Findings suggest that decisions to seek help and to accept help are distinct, and that program factors play a substantial role in treatment engagement and retention.