Voluntary participation is a long-standing tenet of environmental conflict resolution, prescribed at a time when the eventual reach and character of ECR could only be imagined. Today, ECR processes are ubiquitous, varied, and not always voluntary. Voluntary engagement involves choice and perception of fairness instilling commitment, good faith, respectful exchange, and legitimacy. These essential process qualities can be compromised if participation is mandated, yet mandates are sometimes necessary. This disconnect between theory and practice has been extensively examined for court-connected ADR involving civil disputes, but not for ECR involving public disputes. Mediator experience with mandated ECR processes warrants attention.