It's 21 in the United States, and mostly 19 in Canada. Researchers say Canada may have it right.
"We haven't seen an increase in use among youth but we are seeing a difference in how young people are consuming," said the study's co-author. "Understanding that can help to inform public health efforts.
New research discovers an 8% decrease in youth cannabis use in states that legalize for adult use.
A large, independent survey of teens finds significant public health gains.
California teens exposed to medical marijuana ads in the pre-legalization years were affected by the message, researchers say.
For legalization opponents eager to see regulated cannabis markets fail, a new government report out of Washington state doesn't yield much in the way of talking points.
Cannabis consumption by US teenagers fell to a 20-year low in 2016, according to a new report by the federal Substance Abuse and Mental Health Services Administration.
Colorado schools will receive $9.2 million in funds to pay for school health programs, including those designed to prevent underage cannabis use.
Is that 'Hispanics Are Cool' ad the worst teen cannabis prevention campaign ever? You decide: Here are some classic awful ads (and a few that got it right).