We have investigated the mechanical properties of cold sprayed aluminum and the effect of annealing on those properties. Cold spray coatings approximately one centimeter thick were prepared using three different feedstock powders: Valimet H-10, Valimet H-20, and Broadman Flomaster. ASTM E8 tensile specimens were machined from these coatings.  Each material was tested in two conditions: as-sprayed and after a 300°C, 22 h air anneal.  The as-sprayed material showed high ultimate strength and low ductility, < 1% elongation.  The annealed samples showed a reduction in ultimate strength but a dramatic increase in ductility, up to 10% elongation. Microstructural examination and fractography clearly showed a change in fracture mechanism between the as-sprayed and annealed material. Transmission electron microscopy examination of aluminum crystals, grain boundaries, and splat boundaries of as-sprayed and annealed samples will be presented. This data sheads light on the mechanism of ductility increase in annealed cold spray deposites.