This paper examines the contention that learning environments which use IMS Learning Designs can be created by plugging in different components, using generic service descriptions to create the interface between the Learning Design (LD) and the specific tools. There is an alternative viewpoint which claims that generic service descriptions cannot provide the richness required to fully utilize Learning Design. The paper describes the work performed in the SLeD project by the UK Open University and the Open University of the Netherlands. The SLeD project suggests a compromise between the two viewpoints by using generic service descriptions, but recognizing the nature of the current environment through the use of translators, which interact with specific instantiations of services. (Contains 1 figure.)