Each year, diarrheal diseases claim the lives of nearly 2 million people|ninety percent of them children under the age of ve. The problem is especially critical in Africa, a continent that contains ten percent of the world's population, but accounts for forty percent of the deaths of children under age five. Can politically-controversial private sector participation (PSP) in the urban piped water industry improve child health? This paper uses panel data on the sub-national regions of 26 African countries over 1985-2006 to shed light on this question. This is the period during which nearly all African countries that today have PSP in water introduced those arrangements. A xed effects analysis suggests that the introduction of PSP is associated with a decrease in diarrhea among under-five children of about five percentage points, and an instrumental variables analysis suggests that the effects may be even larger. PSP in water also appears to be associated with signicantly higher rates of reliance on piped water as the primary water source, suggesting that increased access may be driving child health improvements.