Data in this document provide information about American children from the beginning of their lives until their fourth birthdays. Compiled largely from federal government sources, the statistics document the birth of infants, the circumstances of their families, the risks to life and health they face in the first years of their lives, the family and community environments in which they develop, and the sources of health care available to them. Varying enormously in depth and in detail, the data with few exceptions are no older than 1980. An introductory summary sketches in broad strokes a group portrait of the nation's youngest children. Section I provides birth statistics and indicates characteristics of child-bearing families. Section II, focusing on infants at risk, concerns congenital malformations, low birth weight, adolescent mothers, exposure in utero to stimulants and drugs, failure to thrive, mental health, behavioral or psychosocial disorders, child abuse and neglect, accidents, and mortality. Section III focuses on working parents and child care, poverty, nutrition, environmental poisoning, divorce and custody, and foster care and adoption. The final section, Section IV, concerns prenatal health care and nutrition, acute and preventive health care for infants and toddlers, and mental health services. (RH)