Newborn screening is the practice of testing every newborn for certain harmful or potentially fatal conditions, such as hearing loss and certain genetic, endocrine, and metabolic disorders that typically are not otherwise apparent at birth. Newborn screening in the United States began in the 1960s. Universal newborn screening has become a well-established, state-based, public health system involving education, screening, diagnostic follow-up, treatment and management, and system monitoring and evaluation. Each year, >98% of approximately 4 million newborns in the United States are screened. Through early identification, newborn screening provides an opportunity for treatment and significant reductions in morbidity and mortality.