This chapter is about an open learning technology specification called Educational Modelling Language (EML, 2000). EML has been designed within the Development-programma of the Open University of the Netherlands as a means to support re-use and interoperability. This language and conceptual ideas behind it have evolved and have gained world-wide acceptance in the shape of the IMS-Learning Design.The chapter elaborates on the requirements for the creation this language and provides several examples of use, accompanied by the representation of these examples in the run-time system Edubox.Published as: Hermans, H., Manderveld, J., & Vogten, H. (2004). Educational Modelling Language. In W. Jochems, J. van Merrienboer, & R. Koper, Integrated e-Learning (pp. 80-99). London: RoutledgeFalmer.