The hype around blockchains—the programming protocol originally created for the Bitcoin—is bidirectional, ranging from apocalyptic predictions of bitcoin energy use that will “destroy our clean energy future” to rosy scenarios that “blockchain technology can usher in a halcyon age of prosperity for all.” The question for policymakers, therefore, is how to ensure that the environment profits in the end. This ELI Research Policy Brief looks at the challenges and opportunities presented by blockchain technology, and it urges environmental professionals to take part in an ongoing conversation with software developers and other stakeholders that will shape the social contract affecting the blockchain’s environmental costs and benefits—plus shape emerging policy and governance responses.