The substantial gains of the early 20th century in the reduction of infant mortality have been followed in recent years in New York city by relatively little decline. Statistical data are presented which suggest where future emphasis in program planning is needed. Certain factors appear to influence infant mortality, such as duration of gestation, weight at birth, age of mother, parity, interval between pregnancies, and certain abnormal maternal conditions. But of prime importance are the socioeconomic influences. Prompt attention to these influences Is most essential for the achievement of substantial reductions in current excessive infant mortality. Social advances directed towards lowering infant mortality have lagged considerably behind modern dynamic biomedical advances.