The USA has historically pioneered the mobilization of market-based instruments for environmental policies; California has been and remains a leading State in the development of such approaches. Such is the case for “conservation banking”, a growing economic activity that aims at producing endangered species habitat credits that firms can buy in order to offset ecological impacts stemming from their activities. These were born in the Sacramento US Fish and Wildlife Service office in the early 1990s. There are currently approximately 150 conservation banks spread on a dozen of States, two-thirds of which are located in California. According to Rea (2017), this Californian success stems from 1) the presence of an important number of endangered species and of important economic development impacting those species; 2) a high density of environmental regulations and institutional levels; 3) an active environmental movement stemming from the civil society watching out for the implementation of the regulations. In contrast, little has been said about the development of this institutional innovation in other States. Beyond organizational and institutional specificities of the “Green State”, how is the diffusion of conservation banking carried out on the US territory? According to what institutional and organizational channels? What does it tell about Californian specificities? What does it tell about market-based conservation policies? The paper explores these questions through empirical study cases of conservation banks outside California as well as grey literature analysis of Federal policy documents. It examines to what extent State regulations may constitute a favorable environment for biodiversity entrepreneurs but also the active role of Californian and federal environmental officers in the diffusion of the model. In short, some States are more attractive for conservation banking development, but this development entails training and tacit knowledge diffusion. This is carried out through Federal funds and Californian field officers’ strong mobilization in favor of conservation banks.