Based on strong research evidence, the most common causes of apparent life-threatening events (ALTEs) are gastroesophageal reflux, lower respiratory tract infection, and seizure. • The minimum initial diagnostic panel for ALTE should include complete blood cell (CBC) count with differential; blood levels of C-reactive protein,glucose, sodium, potassium, urea, calcium,magnesium, ammonia, lactate, and pyruvate; arterial blood gas determination, urinalysis, and toxicology screen; electrocardiography; and assessments for Bordetella pertussis and respiratory syncytial virus in season. • Other testing should be done based on the infant’s clinical presentation and clinician’s degree of suspicion.• Most infants should be hospitalized for cardiorespiratory monitoring for 23 hours after an ALTE. • There is strong evidence that newborns are at higher risk of ALTE and sudden infant death syndrome (SIDS)within the first 24 hours after birth and therefore should be frequently monitored as much as possible while room sharing with their mothers. • Evidence suggests that maternal smoking may place an infant for higher risk of SIDS after an ALTE.