  We develop a nonlinear realisation approach to topologically massive
supergravity in three dimensions, with and without a cosmological term. It is a
natural generalisation of a similar construction for ${\cal N}=1$ supergravity
in four dimensions, which was recently proposed by one of us. At the heart of
both formulations is the nonlinear realisation approach to gravity which was
given by Volkov and Soroka fifty years ago in the context of spontaneously
broken local supersymmetry. In our setting, the action for cosmological
topologically massive supergravity is invariant under two different local
supersymmetries. One of them acts on the Goldstino, while the other
supersymmetry leaves the Goldstino invariant. The former can be used to gauge
away the Goldstino, and then the resulting action coincides with that given in
the literature.
