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Superplasticity is a high temperature deformation phenomenon in which samples exhibit extremely large tensile elongation. The key to obtaining superplasticity is producing grain sizes in the order of ten microns or less, and maintaining these fine structures for reasonable periods of time at temperatures in excess of 50% of the absolute melting point. This is most easily accomplished in two-phase alloys. In most known alloys which exhibit superplasticity, the necessary microstructure is produced by forming operations involving hot or cold working steps. The fine microstructure achieved then contributes to easier hot formability at both high and low strain rates. At high strain rates, where the superplastic effect would not be expected in the tensile test, fine-grained material requires lower working loads than coarse-grained material of identical composition. It has been shown that significant amounts of deformation can be achieved in realistically short periods of time. At low strain rates, where superplasticity is observed in tension tests, the freedom from necking, and the low stresses required for appreciable deformation will probably lead to new forming operations previously impossible in metallic systems. The forming of materials, which will deform superplastically in tension, should not be relegated to the role of a low strain rate laboratory curiosity.