Another new study finds that informal care—using family, friends, or other arrangements—was associated with lower cognitive-ability test scores in kids ages 3 to 6. By contrast, formal, center-based child care had no negative impact compared with remaining in mothers' care. The study examined data from 1,519 single mothers involved in the National Longitudinal Survey of Youth in the States. Household income did not seem to have any significant impact on children's scores, particularly when mothers' educational levels were taken into consideration.