Nacre from seashells is a natural composite with such a well-designed microstructure that its strength and toughness are 20 to 30 times those of its constituents. What controls its remarkable mechanical behavior is poorly understood and there is no design guideline to develop new synthetic composites mimicking nacre. A first effort in this direction will be a throughout investigation of how the microstructure controls the deformation and failure mechanisms of nacre at multiple scales. State of the art experimental techniques and intense modeling are employed at this stage. In a second effort, novel nanocomposites mimicking nacre will be developed. Their design will be based on the morphological and mechanical features that where identified to be key to the strength and toughness of nacre. A combination of ceramic platelets bonded with a softer metallic phase would provide a hard and damage tolerant material ideal for aerospace and MEMS/NEMS applications.