This work presents an experimental investigation to examine the effect of Laponite-a synthetic nanoclay with high plasticity-on the dynamic behavior of sands. The experimental program considers cyclic triaxial and resonant column tests on specimens of pluviated sand and Laponite. Microstructure observation address the granular fabric and the sand-Laponite interactions. Cyclic triaxial tests show that 1% of Laponite impacts the cyclic behavior, improving the liquefaction resistance over one order of magnitude compared to clean sands. Resonant column tests show that the small strain stiffness of the sand (G0) increases with 1% of Laponite. The overall results show that Laponite extends the linear threshold of deformation, reduces stiffness degradation, and delays excess pore pressures. Microstructure observations suggest that Laponite reduces sand particle mobility by the formation of a pore fluid with solid-like properties.