We present a multilevel model of energy transfer in the XeF ground electronic state due to collision-induced VT and dissociation processes. The model, whose parameters are based on experimental results presented here and on other recent data, should be useful in accurate simulations of output efficiency and multiline laser oscillation in XeF. Effective lifetimes of individual ground state levels, applicable to two-level laser models, are determined from the multilevel model. The effective lifetime of the primary lower laser level

is determined to be 4-6 ns for a 1 atm He buffer.