Incremental strain rate, constant strain rate, constant stress, and cone forming tests were systematically evaluated to determine the superplastic formability of titanium alloys. The need for characterizing the strain and time dependences of superplasticity indices and the inadequacy of incremental strain-rate tests for predicting superplastic forming rates were demonstrated. A simplified biaxial conical-die forming test for superplastic forming evaluation of sheet material at elevated temperatures was developed.