Newborn screening for congenital conditions is a public health system composed of testing, follow-up, diagnosis, management, evaluation, and education. As part of the system, follow-up activities play an essential role in facilitating early detection, diagnosis, and intervention for affected newborns. Clinical and Laboratory Standards Institute document NBS02-A2?Newborn Screening Follow-up; Approved Guideline?Second Edition describes the basic principles, scope, and range of follow-up activities within the newborn screening system. It is intended for use by those involved in any aspect of follow-up, including health care providers, parents, and others concerned with the health and welfare of newborns.