This project is about cross-disciplinary (CD) knowledge-generation processes. Research is CD when it combines different disciplines. In the past decades, CD research has gained the interest of research policy makers and funding bodies. At the same time, it became a popular research subject itself. Despite CD research having been widely studied, there is no theory of CD knowledge-generation processes. Yet, such a theory would be very useful and philosophically interesting. Therefore, the aim of this project is to develop a contextualist theory of CD knowledge-generation processes, i.e. a theory that can (i) explicate the CD knowledge-generation processes in specific CD research projects and (ii) provide systematic insight into the similarities and differences between the processes in different CD research projects. The theory will consist of a structured set of explications of common concepts in the science studies literature. Two groups of concepts are important. The first group consists of concepts that refer to actions and products distinguished in disciplines, such as ‘data’, ‘model’ or ‘representation’; the second group consists of concepts that refer to interactions between disciplines such as ‘bridging’, ‘integrating’ or ‘borrowing’. By applying the explications to specific CD research projects, it becomes possible (i) to explicate the knowledge-generation processes underlying individual projects and (ii) to compare the processes underlying different projects.