This paper examines the impact of attrition among the women of the National Longitudinal Survey of Youth 1979 (NLSY79) and children in the NLSY79 Mother-Child Supplement (NLSY79-C). Attrition among the children is nonrandom with respect to mother's marital status, grandfather's completed schooling, and family income. These differences that are related to the probability of attrition do not appear to impact estimates of the effects of family income or maternal employment early in the child's life on either PPVT or BPI standard scores. However, the women who are not interviewed in any child-supplement year and the children for whom supplemental information is never collected appear to be the most disadvantaged. The omission of these children from the NLSY79-C may impact estimates of family characteristics on child outcomes, but because there are relatively few such children, the effects of their omission are likely to be small.