In this paper we develop an Enterprise Systems Implementation Methodology-in-Action framework. The framework is grounded in current views on methodology-in-action (theoretical grounding) and enhanced by an empirical study (empirical grounding). The notion of Implementation Methodology-in-Action, as articulated in this paper, integrates two complementary views that conceptualize a methodology in terms of a technology focusing formalized aspects, i.e. contents as prescribes by designers, and a structural view focusing situational aspects including implementers, implementation context, enterprise systems software, and other individuals participating in the implementation project. The purpose of the framework is to integrate existing gaps in methodology views in order to contribute to a better understanding of implementation methodology. The integrated methodology concept is understood in terms of formalized and situational elements. These elements exert a significant influence on the characteristics and effectiveness of methodology use, and implementers’ actions which may explain differences in ES implementation process’s outcomes. The results from this research helps also participants in ES projects to become aware of the elements which may influence the actions of the users working with implementation methodologies as well as the reasons for these actions in the ES implementation.