Cooperativity plays an important role in metabolic regulation by controlling the rates of enzyme catalyzed reactions. Two basic types of allosteric interactions have been proposed to explain cooperative ligand binding equilibria, and coupled conformational changes in oligomeric enzymes. However, the full range of kinetic cooperative behavior which may result from these allosteric interactions has not been examined rigorously. As a result, certain cooperative phenomena, such as the class of effects known as half-of-the-sites reactivity, may have been interpreted too narrowly. In particular, the possibility that positive equilibrium cooperativity may be accompanied by negative kinetic cooperativity and metastable behavior seems to have been generally overlooked. Our objective in the research proposed here is to clarify the types of kinetic cooperative behavior that may arise from various allosteric interactions.