Traditional approaches to identifying and measuring Information Systems success or failure typically suffer from two deficiencies. First, the measures are taken at a single point in time, usually shortly after the system adoption with a focus on the implementation “success.” Second, the focus is purely on the organisational net gain or loss. The organisation is treated as a single entity, and the Information System itself is relegated to a subservient cog. The power relationship between the organisation and the Information System is left unexplored: in other words, which entity controls the other? This chapter proposes and demonstrates an alternate categorisation model that addresses both deficiencies. The model is applied to a longitudinal study of an implementation of an enterprise system in order to both categorise and explain the outcomes for the host organisation.