Organizations spend a great deal of money and time maintaining enterprise systems (ES) to support their ongoing business needs. The ability to quickly modify these systems, or ES agility, is of paramount importance. Prior research has investigated factors relating to agility at a single point in time however we believe it is important to consider how agility changes over time. We propose a three phase life-cycle that describes how ES agility evolves as businesses address agility challenges. Upon implementation, an ES unity phase exists where an enterprise system exhibits a “clean” design and has a high level of agility. Eventually, system changes will add complexity to the design and the enterprise system will grow; a phase we call ES Expansion. A third phase, ES rigidity, exists when continuous changes to the system make it increasingly difficult to address new agility challenges and the system exhibits limited agility characteristics.