Over recent years, the Environmental Management System (EMS) has become one of the most recognized instruments for operationalizing the CSR concept in companies. The objective of this study is to analyze how this management system is used in companies when they implement the intended green strategies and explore the new green strategies. To achieve this objective, two theoretical frameworks are used: the new institutionalism in organizational analysis and the levers of control of business strategy. The research methodology is qualitative and is comprises of three phases: an exploratory study; a multi-sites case study; and a longitudinal study. The data are analyzed with two softwares: Nvivo 7 and Alceste.