The treatment of latent tuberculous infection (TBI) is a productive and meaningful approach to tuberculosis (TB) control, and an important component of the World Health Organization's (WHO's) new End TB Strategy, especially in high-risk contacts. Unfortunately, although recognized and recommended by the WHO, it continues to be underutilized, and has even been ignored for decades in some high-risk groups, as though it were a taboo. Historical approaches to treating TBI in contacts of drug-susceptible and drug-resistant TB are presented and discussed as compelling experiences. In the United States, the Centers for Disease Control and Prevention have recently shown that a directly observed or even self-administered 12-month regimen to treat TBI with once-weekly isoniazid (INH) and rifapentine is as effective as 9 months of daily INH. Treating TBI in drug-susceptible cases and their contacts should not still be considered taboo-such a short, effective regimen is more akin to the Holy Grail. While not yet confirmed in a clinical trial, treating contacts of drug-resistant TB with the same drugs that are effective in the source case would be expected intuitively and practically to prevent TB in contacts and should be introduced now instead of waiting until clinical trials are completed.