This study investigated elementary school students' environmental knowledge and attitudes, the effects of sociodemographic variables on environmental knowledge and attitudes, and how self-reported environmentally friendly behaviour is related to environmental knowledge, behavioural intentions, environmental affects, and the students' locus of control. Data were gathered by administration of the Children's Environmental Attitudes and Knowledge Scale and Locus of Control scale to 1140 students from 18 randomly selected elementary schools located in urban areas of Ankara, the capital of Turkey. Descriptive results indicated low levels of knowledge, but favourable attitudes toward the environment. The three-way ANOVA provided a significant main effect on students' environmental knowledge of education level of fathers. The sex difference regarding students' attitudes toward the environment was statistically significant in favour of girls. In addition, multiple regression analysis results showed that behavioural intentions, environmental affects, and locus of control, could be accounted as significant predictors of self-reported environmentally friendly behaviour. On the other hand, the present study showed that elementary school students' behaviours toward the environment were independent from their knowledge of environmental issues.