A comprehensive model for explaining scintillation yield in liquid xenon is introduced. We unify various definitions of work function which abound in the literature and incorporateall available data on electron recoil scintillation yield. This results in a better understanding of electronrecoil, and facilitates an improved description of nuclear recoil. An incident gamma energyrange of O(1 keV) to O(1 MeV) and electric fields between 0 and O(10 kV/cm) are incorporatedinto this heuristic model. We show results from a Geant4 implementation, but because the modelhas a few free parameters, implementation in any simulation package should be simple. We usea quasi-empirical approach with an objective of improving detector calibrations and performanceverification. The model will aid in the design and optimization of future detectors. This model isalso easy to extend to other noble elements. In this paper we lay the foundation for an exhaustivesimulation code which we call NEST (Noble Element Simulation Technique).