Neurodevelopmental treatment (NDT) is a technique widely used by physical and occupational therapists in the treatment of neuromuscular disorders; however, quantitative evidence supporting its use has yet to be provided. Several studies have attempted to examine the effects of NDT, but because of poor research methodology, conclusions drawn to support the use of NDT are not based on reliable or well-documented evidence. The purpose of this study was to develop a reliable method of measuring short-term, objective changes in children with cerebral palsy and to measure the immediate effects of NDT and play interventions. A single subject design was replicated with four subjects receiving NDT and nonspecific play over a 5-week time period. Pre- and post-test items were designed to reflect qualitative changes in movement, postural tone, and reflex activity, and were videotaped and coded using interval and time-sampling techniques. The results of this study are equivocal; they neither validate nor invalidate NDT. This study provides a methodology for the investigation of the short-term effects of NDT.