Organizations invest substantial resources in Enterprise Systems (ES) expecting positive outcomes for the organization and its functions. Yet, many ES projects have reported nil or detrimental impacts. The effective management of ES-related knowledge has been suggested as a critical success factor for these ES projects in ES implementations. This paper suggests a theoretical model purporting the importance of a lifecycle wide understanding of knowledge management for Enterprise Systems. The paper provides a path model based on the Adaptive Structuration Theory that captures the dynamic post-implementation knowledge management.