  We study the production of spin 3/2 particles in homogeneous scalar and
gravitational backgrounds from the mode-mixing Bogolyubov method. Considering
only helicity $\pm 3/2$ states we can reduce the problem to a standard Dirac
fermion calculation and apply the standard techniques in a straightforward way.
As an example we consider a supergravity inflationary model and calculate the
spectrum of gravitinos created during preheating at the end of inflation.
