This article summarizes the results of research on the effectiveness of neurodevelopmental treatment (NDT). Both group and single-subject research designs are analyzed, and recommendations are provided for the design of future outcome studies. The research reviewed does not provide conclusive evidence in support of the effectiveness of NDT. However, interpretation of the results of NDT outcome studies is complicated by the lack of a consolidated theoretical base, variability in the treatment provided, and failure to hypothesize what observable and measurable aspects of motor function are most likely to improve with NDT.