Though it feels a bit like shouting into the wind, I’ve nonetheless implored my own children as well as my many students to carefully consider the evidence. Popular opinion, wishful thinking, or even favorable legislative policies are no substitute for data. The world’s best science now indicates that the long-term consequences of adolescent drug use, acting upon a very plastic brain that is highly tuned to news and pleasure while at the same time a bit retarded in terms of self-control, may be grim.