In the analysis, we express the scaled scores in each of the seven domains relative to a sample of “healthy” children by calculating Z-values that are measured as the number of standard deviations below the reference sub-sample mean. The reference group is children who reside in households where the father and mother have 12 years of schooling or higher, the household falls in the upper quartile of the income distribution, the house has cement walls and an iron roof. In the first round, the Z values range from about one fifth to four tenths of a standard deviation below the reference mean for five of the seven domains.

_Anthropometric indicators of nutrition and health status._ The project collected children’s weight and height which were used to calculate Z scores for height-for-age and weight-for-height (i.e., the number of standard deviations below or above the widely-used National Center for Health Statistics standard). Z scores that are more than two standard deviations below the reference population medians for height-for-age and weight-forheight, respectively, are considered to be indicative of stunting and wasting (World Health Organization, 1995). At the baseline, the mean Z scores in Table 5 indicate significant deficits below the reference population median that are, on average, over one and a half standard deviations lower for height-for-age and about three-fifths of a standard deviation for weight-for-height. Thirty-six percent and 7 percent of the children in the sample were stunted and wasted, respectively. While anthropometric Z scores are not significantly different between program and non-program children at the baseline, by Round 3, the Z scores for weight-for-height among program children are about one-fifth of a standard deviation higher.

_Worms._ We measure the percentage of children who had worms six months before the survey. Global estimates indicate that 1.3 billion people carry hookworm ( _Necator americanus, Ancylostoma duodenale_ ), 1.3 billion are infected with roundworm ( _Ascaris lumbricoides)_ , 900 million with whipworm ( _Trichuris trichura_ ), and 200 million with schistosomiasis (Bundy, _et al._ 2001, Miguel and Kremer 2004). Most of those infected are school-age or pre-school age children in developing countries. Children with light helminth infections are often asymptomatic, but more severe worm infections can suffer from iron deficiency anemia, protein energy malnutrition, stunting, wasting, listlessness, and abdominal pain. Schistosomiasis can have more severe clinical consequences, including hepatosplenomegaly (enlargement of the liver and spleen). In a recent study, Miguel and Kremer (2004) find that treatment for worms reduced primary school absenteeism by 25 percent in Kenya. In our sample, about 28 percent of children had intestinal worms in Round 1.

_Diarrhea._ As with worms, diarrhea generally afflicts children below age five in developing countries. Among low- and middle-income countries where 90 percent of all deaths under age five occur, about 20 percent of such deaths are attributable to diarrheal diseases (Black, Morris and Bryce 2003). Diarrhea, which is often accompanied by a loss of appetite, fever and vomiting, can lead to malnutrition and longer term growth 12