The stacking fault energy (SFE) can play a key role in the deformation mechanism (e.g. transformation-induced plasticity and twinning-induced plasticity) of austenitic steels. Therefore, tremendous efforts have been devoted to exploring the evaluation methods and controlling parameters (e.g. alloying elements and temperature) that determine the SFE and its relationship to mechanical twinning. We provide here a summary of recent progress in studies of the SFE of austenite and of unsolved issues that may stimulate further investigation.