Cannabis remains the most popular illicit psychoactive drug used in the US. Some 70-80 percent of 40- 50 year olds have tried it at least once in their lifetime and 18-19 percent of 18-21 years olds have used cannabis in the past month. There are more people in the US who meet criteria for cannabis dependence than have used cocaine in the past month or ever tried heroin; it is of further concern that the use of cannabis under medical marijuana laws continues to expand in the US as dispensaries proliferate. Trends for increased medical use may continue following, e.g., findings that smoked marijuana or a combined-cannabinoid spray can improve symptoms in multiple sclerosis. Studies have shown that acute intoxication with cannabis impairs cognitive function, however cannabidiol (CBD), a constituent of some cannabis strains, may provide some protection from the acute and lasting detrimental effects of cannabis. The studies in this project seek to determine if CBD can attenuate specific cognitive disruptions caused by D9-tetrahydrocannabinol (THC), using a nonhuman primate model. A battery of tests shown sensitive to THC will be used to determine if CBD can block the effects of both acute and chronic administration of THC. The goal is to determine the extent to which CBD might be used to moderate effects of THC in the therapeutic setting, although there are also implications for the recreational user.