Objectives: To examine socioeconomic characteristics associated with planned methadone maintenance treatment (MMT). Methods: We performed multiple logistic regressions using data from the 1998 Treatment Episode Data Set, which tracks admissions for substance abuse treatment. Results: MMT was more prevalent among heroin users than nonheroin users. Among heroin users, females, Hispanics, Southerners, the employed, and those who are not homeless or in jail are more likely to be planned to receive MMT. Among nonheroin users, females were less likely to be planned for MMT. Conclusions: Greater effort may be necessary to extend MMT to vulnerable populations.