In this chapter we provide an overview of the tools required for working with the Learning Design specification (LD 2003). These include editors for creating Units of Learning (UOLs), runtime players, and repositories for storing UOLs. We first examine the context provided by the Valkenburg Group Reference Architecture, identifying those parts which can be handled using general purpose tools, and those which require the development of tools which are specific to LD. We then move on to discuss user roles, and the tools which they require. A framework is offered which enables authoring tools to be situated in terms of their degree of specialization, and the degree to which they require the user to work directly with the specification vocabulary and syntax. We then move on to classify and examine the tools which are specific to LD which have so far been produced, or are currently being developed.