Because of their comparatively large size and long duration, Phase III clinical trials are the most complex and challenging trials to design and implement. They require extensive planning and proactive oversight for successful completion. Despite careful planning, numerous factors often extend the time needed to complete a Phase III trial, including delays in start-up, regulatory approval, or in enrollment of trial participants. Such delays can result in the large carry-over of research dollars and the need for additional years to complete the trial. Therefore, NINDS has developed this policy for providing an initial funding commitment of 2-3 years for the trial in order to establish feasibility before an administrative decision is made to allow the award of the remaining budget and years within the scope of the original council approved application.