The dynamic response of rigid and flexible walls retaining dry cohesionless soil is examined in light of experimental results and analytical elastodynamic and limit analysis solutions. Following a brief review of the problem, experimental findings from three different testing programs on retaining walls are presented, and compared with theoretical predictions based on the above-mentioned approaches. Reasonable agreement is found depending on the assumptions. It is shown that wall flexibility - which is not taken into account in classical design approaches - should be considered to establish the point of application of seismic thrust on the wall. Detailed calculations and set of graphs and charts are presented, which highlight salient aspects of the problem.