This study examines the age of referral and the effect of early intervention for the physically handicapped child. Fifty children were referred before 9 months of age, and they were compared with 55 children referred after 9 months of age. At 18 months of age, the children in the earlier referred group showed greater developmental progress in acquisition of skills in all of the six areas tested: perceptual-fine motor (P less than 0.0003), cognition (P less than 0.0001), language (P less than 0.0004), social-emotional (P less than 0.0001), self-care (P less than 0.0001), and gross motor (P less than 0.0002). The results show that, at least in the short term, there is a critical age for onset of intervention to achieve the most benefit for the developmentally disabled child. Family physicians should be alert to early warning signs of neurological deficits in order to obtain early treatment for these children.