  We describe a general method of calculating the fully differential cross
section for the production of jets at next-to-leading order in a hadron
collider. This method is based on a `crossing' of next-to-leading order
calculations with all partons in the final state. The method introduces
universal crossing functions that allow a modular approach to next-to-leading
order calculations for any process with initial state partons. These techniques
are applied to the production of jets in association with a vector boson
including all decay correlations of the final state observables.
