The book at hand aims to shed light on longitudinal research methods in studies of organizations. A fundamental question immediately arises in the mind of the curious researcher: what is longitudinal research and what methods does it apply in organization research? In this paper, we discuss one type of qualitative longitudinal methodology, namely process research, and describe the challenges its application in an inter-organizational business network setting entails. In revealing the challenges, we confront the definition of longitudinal research generally accepted in the field of social sciences with research applications in the domain of business networks, concentrating on methods of data collection and analysis. The literature on qualitative process methodology and example studies from business networks are employed to support the analysis. In confronting a commonly applied longitudinal methodology with the received view on longitudinal research, we aim to explicate the methodological challenges specific to process studies in network research and, at the same time, to show how the definition of longitudinal research should potentially be extended to offer a legitimate home to the various qualitative and quantitative research approaches that study organizations longitudinally.