Australia and Canada have been active participants in international climate change negotiations since the early 1990s and have often shared negotiating positions. This paper discusses why, in spite of considerable similarities in national circumstances, the Canadian government chose to ratify the Kyoto Protocol in 2002, while the Australian government decided against doing so. It is argued that a range of factors led to a narrower conception of the national interest in the case of Australia, which encouraged a focus on the short-term, economic costs of implementing the Protocol. [ABSTRACT FROM AUTHOR]