  Continuing the analysis in a unified scheme for treating generalized
superselection sectors based upon the notion of selection criteria for states
of relevance in quantum physics, we extend the Doplicher-Roberts superselection
theory for recovering the field algebra and the gauge group (of the first kind)
from the data of group invariant observables to the situations with spontaneous
symmetry breakdown: in use of the machinery proposed, the basic structural
features of the theory with spontaneously broken symmetry, are clarified in a
clear-cut way, such as the degenerate vacua parametrized by the variable
belonging to the relevant homogeneous space, the Goldstone modes and
condensates.
