Environmental educators often maintain that primary school education should endeavour to improve and protect the environment through producing an 'environmentally informed, committed and active citizenry', yet existing research shows that the implementation of environmental education in primary schools is problematic and has had limited success. The reasons for these shortcomings are far from clear, with present research merely speculating about barriers to effective implementation. To this extent, there is a dearth of empirical research about primary school teachers' knowledge of environmental education and the degree to which teachers' knowledge inhibits environmental education practice. As such, this article investigates Australian primary school teachers' knowledge about environmental education, and in so doing utilises a combined-methods approach and the theoretical concept of 'ecological literacy' (eco-literacy) to assess primary school teachers' knowledge (and beliefs) about environmental education. Based upon the findings of this study, we contend that Australian (specifically Queensland) primary school teachers are likely to be functioning at a 'knowledge' level of ecological illiteracy and/or nominal ecological literacy. Furthermore, such primary school teachers tend to dismiss the importance of knowledge, preferring to focus upon attitudes and values in the teaching of environmental education. As shown in existing research, these trends can be placed in wider theoretical debates to do with knowledge and education generally. In any case, such levels of ecological literacy are inadequate if ecologically literate students and thus an ecologically literate citizenry are to be achieved within schools.