In 2007, Danone embarked in an ambitious environmental accounting program to find a new way to account for their environmental performance. The main case comprises three complementary parts (A, B, and C) describing how Danone implemented the different bricks of a full environmental accounting management system, which has consolidated until today in a company-wide initiative. It highlights how they built an entire carbon management system (A), what human organization for carbon accounting they chose (B), and which stakeholders they involved in their project (C). Two optional follow-on parts present (1) the main challenge Danone had to face and its consequences in terms of carbon accounting standards convergence and (2) the way Danone professionalized their environmental accounting system.