  Supergravity provides the effective field theories for string
compactifications. The deformation of the maximal supergravities by non-abelian
gauge interactions is only possible for a restricted class of charges.
Generically these `gaugings' involve a hierarchy of p-form fields which belong
to specific representations of the duality group. The group-theoretical
structure of this p-form hierarchy exhibits many interesting features. In the
case of maximal supergravity the class of allowed deformations has intriguing
connections with M/string theory.
