  I summarize the derivation of a set of Feynman rules appropriate for the
perturbative description of the nonequilibrium dynamics of the
symmetry-breaking phase transition in $\lambda\phi^4$ theory in a
Robertson-Walker universe. The approximation scheme I develop provides for a
treatment of dissipative effects which are essential to an adequate description
of the nonequilibrium state. It also provides for the emergence from an
initially symmetric state of a final state exhibiting the properties of
spontaneous symmetry breaking without the introduction by hand of any explicit
symmetry breaking.
