Previous studies have suggested that the administration of a marihuana extract to pregnant rats and mice may cause an increase in fetal teratology and neonatal mortality. Prenatal exposure of the fetus to marihuana may also affect the behavior of offspring in more subtle ways. According, dose-response relationships between prenatally-administered marihuana extract and many aspects of the cognitive function of the adult rat will be studied using a battery of behavioral tests including shock avoidance, maze, and brightness discrimination learning, open field activity, and schedule-controlled behavior. The experimental design will allow for the identification of the "critical periods" during which exposure of the fetus to the drug can be expected to produce untoward behavioral effects after birth. To this end independent groups of animals will be exposed to the drug during different trimesters of gestation. Following the characterization of these prenatally-induced behavioral effects, studies will be conducted with the individual cannabinoid components of the extract to identify those compounds that may be responsible for the changes in behavior.