Various states have legalized marijuana for medical purposes and/or decriminalized recreational marijuana use. These changes coincide with a decrease in perceived harmfulness of the drug and an increase in its use among youth. This change is of critical concern because of the potential harmful impact of marijuana exposure on adolescents. Marijuana use has been associated with several adverse mental health outcomes, including increased incidence of addiction and comorbid substance use, suicidality, and new-onset psychosis. Negative impacts on cognition and academic performance have also been observed. As the trend toward legalization continues, the pediatric community will be called on to navigate the subsequent challenges that arise with changing policies. Pediatricians are uniquely positioned to provide innovative care and educate youth and families on the ever-evolving issues pertaining to the impact of marijuana legalization on communities. In this article, we present and analyze the most up-to-date data on the effects of legalization on adolescent marijuana use, the effects of adolescent use on mental health and cognitive outcomes, and the current interventions being recommended for use in pediatric office settings.