We present a systematic review on the effect of early intervention, starting between birth and a corrected age of 18 months, on motor development in infants at high risk for, or with, developmental motor disorders. Thirty-four studies fulfilled the selection criteria. Seventeen studies were performed within the neonatal intensive care unit (NICU) environment. Eight studies had a high methodological quality. They evaluated various forms of intervention. Results indicated that the Newborn Individualized Developmental Care and Assessment Program (NIDCAP) intervention might have a temporary positive effect on motor development. Twelve of the 17 post-NICU studies had a high methodological quality. They addressed the effect of neurodevelopmental treatment (NDT) and specific or general developmental programmes. The results showed that intervention in accordance with the principles of NDT does not have a beneficial effect on motor development. They also indicated that specific or general developmental programmes can have a positive effect on motor outcome. We concluded that the type of intervention that might be beneficial for infants at preterm age differs from the type that is effective in infants who have reached at least term age. Preterm infants seem to benefit most from intervention that aims at mimicking the intrauterine environment, such as NIDCAP intervention. After term age, intervention by means of specific or general developmental programmes has a positive effect on motor development.