  The purpose of this article is to give the first complete proof of the
Whittaker Plancherel Theorem. The proof uses Harish-Chandra's Plancherel
Theorem for a real reductive group and its exposition can be used as an
introduction to Harish-Chandra's ideas. The proof follows the basic ideas in
the author's original attempt in his second volume on real reductive groups. An
error in the calculation of the Whittaker Transform of a Harish-Chandra wave
packet is fixed using a result of Rapha\"el Beuzart-Plessis.
