The interview methodology is a widespread methodology used by researchers to develop knowledge about projects, project management, and temporary organising. However, an interview study may be performed and assessed differently. This is because the interview methodology, as all research methodologies, builds on assumptions about the phenomenon studied and about how knowledge about this phenomenon may be developed. In this chapter, we describe four types of interview studies that researchers may engage in: the objective, the interpretative, the dialogic, and the critical. These may be understood as ideal types, based upon which studies may be modelled. The ontological and epistemological assumptions underlying the four types differ, which affects the craft and the assessment of the quality of the finished study. The skilled project researcher needs to be aware of this to carefully choose the way she sets up and performs an interview study. © 2024 selection and editorial matter, Beverly Pasian and Rodney Turner; individual chapters, the contributors.