This paper describes a method of introducing ethics to a second-year class of civil engineering students. The method, known as a "structured controversy", takes the form of a workshop where the students assume the identity of stakeholders having an interest in a proposed development in an environmentally sensitive region. The instructor enhances the workshop by deliberately feeding incorrect information into a catalogue of facts that each stakeholder has at their disposal. After the workshop, the instructor draws out three ethical frameworks from which the stakeholders operate. A key component of the exercise is that the students do not know beforehand that the environmental workshop is being used to introduce ethics. When the connection is revealed, the students appreciate that much of their behaviour during the role-play was because they inadvertently adhered to an unknown ethical platform. Since it is an environmental simulation, an explicit connection can be made to the debate over "who" to include in the moral community. In addition, a link can be drawn to the notion of sustainable development which, in this paper, is advocated as an ethical rather than a technical concept. (Contains 1 figure.)