The application of the concept of sustainable development in development co-operation has created a need for additional professional training in The Netherlands. Sustainable development is a relatively new concept. Applying this concept in development projects and policies requires professionals with a interdisciplinary, analytical and environmentally-conscious approach. However, most of today's development experts have professional biases. Is it possible to teach development experts the sustainable development approach in a short training course? This article deals with the implementation of the concept of sustainable development for professional training purposes in the field of development co-operation. It describes the development of a training programme and its two central frameworks, illustrated with case studies. It also reports on experiences and makes evaluative remarks about the impact of the training on the participants. Since 1991, a one-week training programme has been used to update project staff and desk officers. The training offers: (1) an overview of backgrounds and policies in the field of environment and sustainable development; (2) theory and tools to analyse problems of unsustainability; and (3) theory and tools to (re-)design environmentally-sound activities, projects and programmes.