Public sentiment and laws around the use of cannabis continue to become more permissive in the United States alongside a growing perception of effective medicinal applications. Yet, there is a robust literature documenting cannabis-associated worsening of neuropsychological functioning. What does the current scientific research suggest about the type and magnitude of neuropsychological side-effects from recreational and medical use of cannabis? How have results from meta-analyses and large longitudinal studies contributed to our current understanding? Are findings similar in adolescent and adult samples? What factors contribute to poorer or better neuropsychological outcomes? What future research is needed to understand who may be more vulnerable or resilient to adverse effects of cannabis on neuropsychological functioning. This seminar will provide an update of the scientific literature addressing the aforementioned questions.