During an interdisciplinary longitudinal study, the social development and mastery of feeding skills of 89 young Down syndrome children were investigated. Sex, cardiac status, and muscle tone of subjects and parental follow-through data were examined for potential influence on Vineland Social Maturity Scale scores and on a selected subset of feeding milestones. The revealed that young Down syndrome children attained significantly higher scores on the Vineland and achieved most feeding milestones much earlier if they had no or only mild congenital heart disease, if their parents followed-through appropriately with furnished guidance, and if they had "good" muscle tone.