The history of the New York City Department of Health Bureau of Tuberculosis Control Program, and the events leading to the adoption of wide-scale directly observed therapy (DOT) in 1992 are described. The organization and role of Department of Health and non-Department of Health directly observed programs are discussed. Details are provided regarding the Department of Health's program: the use of standard treatment and program protocols, the use of incentives and enablers, a profile of the successful DOT worker, the detention program, and other issues. Program data and outcomes from 1992 through 1995 are presented, along with some of the challenges and questions for the future.