Rangeland ecologists have been debating the validity of two current paradigms for the evaluation of vegetation dynamics on rangelands. This debate frequently contrasts the conventional model of continuous and reversible vegetation dynamics (range model) with a more contemporary model that can accommodate discontinuous and non-reversible vegetation change (state-and-transition model). Keywords: equilibrium systems, event-driven dynamics, non-equilibrium systems, paradigm shift, range condition, rangeland ecology, state-and-transition model, threshold.