Cannabis is one of the most widely used illicit drugs in the United States, including among America’s youth. Despite the extensive use of cannabis, research on this drug has been limited mainly because it has been viewed as a “safe” recreational substance. This article reviews the research literature on cannabis published in English between 1994 and 2004 to identify pertinent information regarding use levels and behavioral and psychiatric problems associated with cannabis use. The research indicated high levels of cannabis use; studies show that between 1976 and 2002, almost half of all 12th graders in the United States had been exposed to cannabis. Further, evidence suggests that early and regular cannabis use may be associated with subsequent depression, suicidal behavior, and psychotic illness, including schizophrenia. Although research on cannabis has increased in recent years, there is scant research available on cannabis treatment. Moreover, while the research reviewed here indicates a connection between early and regular cannabis use and psychiatric illness, there is still much debate concerning the causality of this relationship. Future empirical research should continue probing the relationship between child and adolescent cannabis use and deleterious psychiatric and behavioral outcomes. References