The organizing framework behind this text is the Testing Maturity Model (TMM) which was developed by a research group headed by the author at the Illinois Institute of Technology [1–5]. The TMM was designed to be used by software development organizations to assess and improve their testing processes. It is also useful as a model that illustrates in stages how a testing process should grow incrementally in proficiency. This property makes it useful as an educational tool to introduce testing con cepts, principles, and best practices in an evolutionary manner. Chapter 1 describes several aspects of the TMM including its basic structure and maturity levels. I offers more details on the maturity levels and their relationship to the tools in the Testers’ Workbench.