Marijuana is one of the world’s most commonly used illegal drugs. There are approximately 300 million users worldwide and 28 million users in the United States (Diaz, 1997). Marijuana comes from a plant called “Cannabis sativa.” The chemical in this plant that produces the altered states of consciousness is called “delta-9 tetrahydrocannabinol” or “THC.” Marijuana is usually smoked like a cigarette, but it can also be cooked into baked goods like brownies or cookies or brewed like a tea. THC is also contained in “hashish” (hash) which is the resin from the marijuana plants. Hash is usually smoked in a pipe. Other names for marijuana include: grass, pot, reefer and weed.