Three intervention processes being applied to environmental disputes -- facilitation, mediation, and policy dialogue -- are described, and similarities are noted. Some similarities are that (1) the intervener claims to be impartial about the disposition of the dispute, (2) intervener expertise relates to the processing of the dispute rather than to scientific or technical knowledge related to the dispute, and (3) the intervener seeks to achieve mutually derived and acceptable outcomes. The basic ethical principle that the intervener should espouse, self-determination for all parties to a conflict, is emphasized. Additionally, three elements that ensure true self-determination for the parties are described: information, relative power or influence, and opportunity for involvement. Finally, three ethical caveats are presented for the intervener. First, when the disputants are inexperienced in the use of an intervention process, the intervener has a particular ethical responsibility to guide them. Second, the less equal the relative power of the parties, the greater is the ethical responsibility of the intervener. Third, the greater the impact of the settlement on those not 'at the table,' the greater is the ethical responsibility of the intervener. Ten footnotes are provided.