Two types of knowledge are essential in method engineering: knowledge of IS development and knowledge of method development. In this chapter we focus on the first of these, information system development, and especially on development methods and tools.

In the following we shall first define ISD and characterize the role of methods and tools in its enactment. Second, in Section 2.2 we shall survey methods based on their characteristics and alternative structures of method knowledge. Third, in Section 2.3 we shall clarify the mutual relationship between modeling tools and ISD methods, referred to here as method-tool companionship. Fourth, in Section 2.4 we shall discuss the paradoxes of method use by looking at the acceptance of methods in general and commercial “text-book” methods in particular. This leads us to propose an alternative view of method development, which helps explain the reasons for local method development.