  In this contribution we present results from the NLO computation of the
production of a $W$ boson in association with three jets in hadronic
collisions. The results are obtained by combining two programs: {\tt BlackHat}
for the virtual one-loop matrix elements and {\tt Sherpa} for the real-emission
contributions. We present results for the Tevatron and the LHC, and address the
issue of the choice of a common factorization and renormalization scale for
this process.
