A variety of factors have been found relevant in understanding treatment entry and dropout from treatment. Individual and interpersonal factors fall into the general categories of severity of substance abuse and psychological problems, social stability, motivation, and treatment characteristics. Generally, individuals with more severe substance abuse problems have been found more likely to drop out of treatment. The way in which treatment services are delivered can significantly affect dropout. This study extended the work of previous researchers that examined attrition from specific types of treatment such as therapeutic communities and inpatient alcohol treatment. Participants completed a core battery of evaluation of instruments at the central intake unit (CIU). Univariate analysis showed that individuals with a shorter wait after assessment were more likely to attend an initial treatment appointment. Those that reported a history of physical or sexual abuse or were on probation were significantly more likely to drop out of treatment early. Multivariate analysis showed that persons with a co-morbid psychiatric diagnosis and those referred to outpatient rather than residential care were less likely to enter treatment. Persons on probation and with a history of physical or sexual abuse were more likely to be early treatment dropouts. Decisions to seek help and to accept help were distinct. Program factors appeared to play a substantial role in treatment engagement and retention. Although treatment retention may be improved by attending to at-risk individuals, examination of individual characteristics alone is not enough to understand the engagement process. 3 tables, 33 references