This paper examines the historic and contemporary role of one Canadian environmental non-governmental organisation (ENGO) in the operationalisation of sustainable tourism. In particular, the extent to which the ENGO has contributed to coordinated, cooperative policy development and implementation within this policy domain is examined. While coordinated policy making is widely accepted as a basis for environmentally sustainable tourism development, organisations may contribute more towards this goal by choosing not to be included, or by being excluded from, this framework of coordination. This paper uses an interorganisational relations perspective to explore the position, influence and relationships of one ENGO active within Canada's national park tourism policy domain. Implications are drawn for the implementation of sustainable tourism within protected areas.