This article documents child suicide rates from 1980 to 2020 in the United States using the National Vital Statistics System Multiple Cause of Death database. After generally declining for decades, suicide rates among children aged 10–17 accelerated from 2011 to 2018 in an unprecedented rise in both duration and magnitude. I consider the role of the illicit opioid crisis in driving this mental health crisis. In August 2010, an abuse-deterrent version of OxyContin was introduced and the original formulation was removed from the market, leading to a shift to illicit opioids and stimulating growth in illicit opioid markets. Areas more exposed to reformulation—as measured by pre-reformulation rates of OxyContin misuse in the National Survey on Drug Use and Health—were more affected by the transition to illicit opioids and experienced sharper growth in child suicide rates. The evidence suggests that children's illicit opioid use did not increase, implying that the illicit opioid crisis engendered higher suicide propensities by increasing suicidal risk factors for children, such as increasing rates of child neglect and altering household living arrangements. In complementary analyses, I document how living conditions declined for children during this time period.