Abstract While courts and their pronouncements are a natural focus for lawyers and those who study and write about the law, in reality only a tiny fraction of disputes ever make it to court, and still fewer result in a substantive judgment on the merits of the case. In practice, the vast majority of disputes are resolved without ever reaching the steps of the courtroom, and this holds true also for disputes involving environmental principles. Indeed, for reasons that are discussed further below, dispute resolution by non-judicial means has, since the birth of environmental law, played a central role, and the importance of that role continues to increase. Such dispute resolution ranges across non-formalised consultation, diplomacy, and negotiation, to more formalised methods such as mediation, arbitration, and the use of quasi-judicial dispute resolution bodies established to ensure the implementation of individual environmental treaties. The present chapter explores the key forms of non-judicial dispute resolution of environmental disputes, the benefits and weaknesses of non-judicial approaches, and recent innovations in the area of particular note at international and regional levels, considering inter-State and State-citizen dispute settlement mechanisms.