We are in the midst of a teen mental health crisis. Since 2011, the rate of U.S. hospitalizations for preteen girls who have self-harmed is up 189 percent, and with older teen girls, it’s up 62 percent. Tragically, the numbers on suicides are similar — 151 percent higher for preteen girls, and 70 percent higher for older teen girls. NYU social psychologist Jonathan Haidt has spent the last few years trying to figure out why, working with fellow psychologist Jean Twenge, and he believes social media is to blame. Jonathan and Jean found that the mental health data show a stark contrast between Generation Z and Millennials, unlike any demographic divide researchers have seen since World War II, and the division tracks with a sharp rise in social media use. As Jonathan explains in this interview, disentangling correlation and causation is a persistent research challenge, and the debate on this topic is still in full swing. But as TikTok, Instagram, Snapchat and the next big thing fine-tune the manipulative and addictive features that pull teens in, we cannot afford to ignore this problem while we sit back and wait for conclusive results. When it comes to children, our standards need to be higher, and our burden of proof lower.