Abstract The one major shell fermion dynamical symmetry model (FDSM) is extended to multiple shells. We term the resulting theory the supershell-FDSM (SFDSM). Many basic features of superdeformation emerge naturally from the SU 3 fermion dynamical symmetry of this model. It is found that the dynamical Pauli effect plays a vital role in the formation of low-lying superdeformed states and provides a simple criterion for predicting where SD strength is most likely to occur. The SFDSM suggests that many-body correlations that are discarded in the usual mean-field theories are responsible for the widespread occurrence of identical bands in superdeformation. In this model the superdeformed ground band is not the usual unaligned band, but a D-pair aligned (DPA) band that sharply crosses the excited bands. We propose that the DPA band may be a key to understanding many superdeformation properties, including the sudden decay-out of superdeformed yrast intensity.