This article describes factors that can affect the refer rate for otoacoustic emission (OAE) based newborn hearing screening, including the population of infants being screened, the adequacy of probe fit, software options used, external ear conditions, screener training, and baby handling. The effect of the infant's age on screening outcomes is also discussed using results of screening for 1328 regular nursery newborns, ranging in age from 6 to 60 hours, who were screened with transient evoked otoaoustic emissions (TEOAE) prior to hospital discharge. The youngest infants (6-9 hours old) were as likely to pass (90% pass rate) as the infants who were 24-27 hours old (94% pass rate). The results of this study are consistent with reports from many TEOAE-based screening programs that have demonstrated that acceptably low refer rates (mean = 6.9%) can be obtained when appropriate screening procedures are followed.