SUMMARY In spite of marijuana being the most widely used illegal drug among women of reproductive age there is a relative paucity of literature dealing with this topic. Of the data available, particularly in offspring beyond three years of age, most is generated by two ongoing cohort studies with very different populations. Both have reported similar findings. Up to approximately 3 years of age there appears to be very little impact upon the offspring. Beyond that age, in utero cannabis exposure does not impact upon standardized derived IQ scores but is negatively associated with attentional behavior and visual analysis/hypothesis testing. These findings are hypothesized as prenatal marijuana exposure having a negative influence on aspects of executive function-a “top-down,” multifaceted cognitive construct involved in organizing and integrating specific cognitive and output processes over a interval of time. The results and their interpretation are examined in terms of behavioral teratogenic effects (or ...