Environmental education was first formally introduced to Malaysian schools in 1986. Its implementation since then has been limited owing to various constraints facing teachers, and its success in achieving stated environmental education objectives remains uncertain. In view of this, an empirical, exploratory, descriptive study was undertaken to gauge levels of environmental understanding, awareness and knowledge, and the involvement of secondary school students in sustainable consumption practices. A survey was conducted using a self-administered questionnaire with 306 students who were randomly selected from four secondary schools in the state of Johor, Malaysia. The instrument had sections addressing demography, sources of environmental information, concept of environment, environmental knowledge, environmental awareness and concern, sustainable consumption behaviours, and nature-related activities. The data illustrate that students were aware of, but only moderately concerned with, environmental issues. Only 10% of the students were able to define environment in terms of a relational conception (as opposed to an object). The adoption of Janikowski's four principles of sustainable consumption (selection, reduction, maximization and segregation) in their daily living was modest. Environmental education "in" and "with" nature experiences was found to be minimal among the respondents. The relationship between variables was also investigated. The findings showed that environmental education had raised the environmental consciousness of students but was rather ineffective in changing action and behaviour patterns. Ways of enhancing understanding and participation of Malaysian school students in environmental education and sustainable development are also proposed. (Contains 5 tables.)