Thousands of children, some of whom are as young as eight-years-old, are working in Tanzanian small-scale gold mines, with grave risks to their health and even their lives. They dig and drill in deep, unstable pits, work underground for shifts of up to 24 hours, and transport and crush heavy bags of gold ore. Child laborers, as well as children living near mining sites, are also at serious risk of mercury poisoning. Mercury attacks the central nervous system and can cause lifelong disability to children, whose developing bodies are more easily affected by the heavy metal. Most adult and child miners are unaware of these health risks and health workers lack training and facilities and are not equipped to diagnose or treat mercury poisoning. Working in the mines interferes with children’s education. Children working in mining sometimes skip classes or drop out of school altogether. The Tanzanian government should curb child labor in small-scale mining, including at informal, unlicensed mines, and the World Bank and donor countries should support these efforts.