In this paper we present standardized measures of tenth grade students' knowledge, attitudes and behaviours concerning sustainable development as those concepts are understood in the United Nations Educational, Scientific and Cultural Organization, and we test the hypothesis that knowledge and favourable attitudes toward SD lead to favourable behaviours. Using a fairly representative random sample of 1,551 tenth grade students from the province of Manitoba, Canada, we crafted 3 indexes. There is a 20-item Index of Knowledge of SD with a good Cronbach alpha = 0.89, a 15-item Index of Attitudes Favourable Toward SD with alpha = 0.84 and a 15-item Index of Behaviours Favourable Toward SD with an alpha = 0.83. About 21% of the variation in our Behaviours Index scores could be accounted for by our Knowledge Index and Attitudes Index scores.