In the near stall regime, when the airflow over a wing is partially separated, the shed- ding of coherent structures can result in large unsteady aerodynamic loads. Under such conditions high aspect ratio wings, such as found on modern composite airplanes, will experience some degree of structural motion normal to the chord line. Simulations and experiments for a chord-based Reynolds number of Re=200k were carried out for a wing section with X-56A airfoil to investigate the effect of a harmonic heaving/plunging motion on the unsteady aerodynamics. The reduced frequency of the structural motion was in the range 0.35<k<1.4 and the amplitude was 3.2 to 9.6% of the chord length. For 10deg angle of attack the unsteady lift for the plunging motion is in good agreement with Theodorsen's formula. As the angle of attack is increased up to 16deg the flow over the top-surface of the wing begins to separate intermittently. The timing of the flow separation and the shedding of the resultant stall vortex were found to depend on the frequency and amplitude of the structural motion. For 12 and 14deg angle of attack, high frequency blowing and suction through a spanwise slot near the leading edge is shown to delay transition and to improve lift and reduce drag. Steady spanwise disturbances that were introduced at the leading edge were found to promote flow separation and strengthen the stall vortex. At 16deg angle of attack the wing section is fully stalled. However, when subjected to a low amplitude plunging motion, the flow intermittently reattaches and lift is increased in the mean. Finally, preliminary two-dimensional fluid structure interaction simulations were carried out that revealed a coupling between the vortex pattern on the suction surface and the structural motion.