From 2005 to 2012, injuries to children under five increased by 10%, possibly because smartphones distract caregivers from supervising children. I exploit the expansion of AT&T's 3G network in both a difference-in-differences and a triple difference framework and find that hospitals experienced a 5% increase in emergency department visits for children ages 0–5, but none for children ages 6–10, after getting 3G. Age-specific injury patterns on playgrounds, from poisoning, and in sports further support the conclusion that smartphones distract caregivers.