Traditionally, the development of computerbased instructional materials has relied on the use of programming languages and computer programmers. This has often made development prohibitively difficult, time-consuming and expensive. It has also meant that it has been difficult for enthusiastic subject experts to develop their own teaching materials. In order to address these problems a wide variety of authoring systems have been produced which allow the rapid development of instructional materials by reducing the amount of low-level coding necessary for their implementation. A problem which arises from this proliferation, however, is that subject experts find it hard to identify the best tool for a particular development task. This book has been written essentially with the aim of providing potential educational software authors with a brief background to instructional design, an overview of some currently available authoring systems, and a means by which an informed choice of authoring system can be made.