This study tested the effects of the sedative-hypnotic drug triazolam (Halcion) on the ability to inhibit behavior in humans. Thirty adults practiced a stop-signal task that measured their ability to inhibit and activate behavioral responses on a choice reaction time task. Equal numbers of participants (i.e., n = 10) then received either 0.25 mg, 0.125 mg, or 0 mg (placebo) of triazolam under double-blind conditions and performed the task intermittently over a 3-hr period. In accord with the hypothesis, triazolam reduced response inhibitions and increased the time required to inhibit a response. The drug also slowed the activation of responses. The findings contribute to the understanding of the basic behavioral mechanisms by which sedative-hypnotic drugs can produce states of behavioral disinhibition in some individuals.