Environmental governance implies creation of novel interdependencies among actors and actions, and this innovation and diversity presents challenges. One of these challenges is the maintenance of legitimacy. To understand processes of legitimation at the level of individual organizations and at the level of the larger assemblages represented by governance arrangements, we develop a conceptual framework that analyzes accountability relationships. Within this framework, we use artifacts of accountability, material representations of accountability relationships, to understand the creation, maintenance, and erosion of legitimacy. We study the creation and administration of a multifunctional forested landscape in New Hampshire, USA. Empirical assessment of the varied institutional logics that structure and contribute to legitimacy in this material and organizational landscape allows us to advance understanding of persistence, change, and failure of environmental governance arrangements.