Tuberculosis (TB) is a serious infection that can affect the lungs and other parts of the body. The usual way to treat TB is to take 4 medicines by mouth every day for 2 months, then take 2 of the same medicines for 4 more months, for a total of 6 months. The purpose of this study is to see if taking 4 months of TB medicines is as effective in curing some TB patients as taking 6 months of TB medicines. Study participants will include 758 human immunodeficiency virus (HIV)-non-infected individuals, ages 18-60. Participants will be treated with 4 standard drugs called isoniazid, rifampicin, pyrazinamide and ethambutol. All individuals will take TB medicines for at least 4 months. After 4 months of treatment, if no TB germs are growing in sputum samples, participants will be assigned to either stop taking TB medicine (4 months of treatment) or to continue taking TB drugs for 2 more months (6 months of treatment). Participants will be involved in study procedures for up to 30 months.