The findings indicate that overall acute cannabis negatively affects cognitive abilities, including executive control, decisionmaking, and planning, all of which are important components of goal-directed behavior. Specifically, the results revealed disruption of the Go/No Go contingent negative variation (CNV), which indicates acute cannabis intoxication. This cannabis intoxication was accompanied by impairment of brain function related to goal-directed activity. The effects of acute cannabis on Go/No Go CNV resembled effects reported in patients with lesions of the dorsolateral prefrontal cortex. Results also suggest a neural mechanism that causes disinhibition of angry aggression, which may predispose cannabis users to acts of violence while in a psychotic state. The findings are preliminary and should not be taken to mean that all adolescent cannabis users are at increased risk for impairments in goal-directed behavior or violence. The preliminary findings of this study warrant more large-scale studies of the negative consequences of cannabis use. Participants were five men between the ages of 22 and 36 years who were recruited from a larger study assessing a salivary measure of THC. All participants reported regular use of cannabis, defined as 2 to 12 times monthly, no other illicit substance use, and no history or symptoms of mental disorder. Participants abstained from cannabis use for a period of 7 days preceding the study. Each participant underwent a Go/No Go CNV recording and EEG was recorded on the left and right central sites and on the vertex. A prefrontal channel monitored blinks and eye movements. Three recordings were done: (1) baseline; (2) while participant smoked cannabis; and (3) 20 to 40 minutes after smoking marijuana. Participants completed a mood adjective checklist prior to and immediately after each recording. Figure, references