Chapters 4, 5 and 6 describe three stages of an intellectual evolution from a dispersed and ad hoc pattern of performance-related activities to a fully fledged and integrated model of Performance Management (Chapter 6), and perhaps even beyond Performance Management to Performance Governance (Chapter 9). To facilitate the analysis we have created four ‘ideal types’ in the Weberian meaning of the word (see Introduction to Appendices, pp. 211-219), as pure types of modelled stages (Bouckaert and Halligan 2006). In reality they do not exist as such, but it is useful to have these pure types to classify realities which consist of mixed, hybrid and blended versions of these pure modelled stages.