The results of an experimental program directed at understanding the unsteady mean and turbulent flow in a large-scale -l-Vi stage research turbine are presented. High response instrumentation and the phase-locked averaging data reduction technique were utilized to acquire data having high spatial and temporal resolution. These data included the unsteady three-dimensional distribution of mean and turbulent velocities and total and static pressures. The data between the guide vane and the rotor and downstream of the rotor are presented herein. The flow downstream of the vane was found to be essentially steady and was dominated by large Reynolds stresses in the wakes and secondary flow regions. In contrast, the flow downstream of the rotor was highly unsteady. Two different rotor exit flow regimes were identified, corresponding to maximum and minimum interaction of the rotor leading edges with the upstream vane wakes. During the maximum interaction, the vane wakes merged with the rotor wakes, the midchannel flow was fairly uniform, and two strong secondary flow vortices were present. During minimum interaction, the vane wakes entered the rotor passages between airfoils, the midchannel flow was nonuniform, and the secondary flow vortices were less well defined.