Methods are means to help designers achieve desired change as efficiently and effectively as possible. Methods can be used to do so in the context of learning - to help teach students how to design on a professional level. Methods can also be used in the context of performance - to help designers perform better at what they already do (well). Methods should be seen as mental tools that influence the thinking patterns and mental models of designers. If we accept that methods function via a designer’s mind, we can see that method usage is a human activity in which the designer is the user. This seems to be an obvious fact to be aware of for a discipline that is characterized by its focus on the user of the products and services they design; yet, quite remarkably, many design researchers have paid little attention to the users of their methods. Instead, most design research is aimed at ‘directly’ improving the design process through methods, often ignoring differences between designers, design contexts and design objects. In this thesis, I argue that an important reason for the current state of design methodology is our marginal understanding of the phenomenon of method usage. The thesis aims to contribute to a more detailed understanding of method usage in design, from the perspective of its central actor: the designer. With that, the thesis hopes to lay a foundation for a more designer-centered methodology that inspires researchers to deliver more valuable and useful methods to the design community and that inspires designers, design educators, design managers and design policy makers to re-think the way they employ and promote design methods in their practices.