The literature on capital budgeting and investment proposals is rich with techniques, such as portfolio management and stage-gate project management, which rely on a rational approach to strategic capital investment projects. There is, however, a lack of research on the process of managing and coordinating strategic capital investment projects where investment proposals and decisions are seen as human constructions. The controller is an important but seldom noticed actor in this process. This paper draws on a pragmatic constructivist framework to create an understanding of the controller role in strategic capital investment projects and how the controller acts to contribute to create a functioning construct causality in such projects. We conducted a case study of a mining company, which had recently decided on strategic capital investments resulting in the moving of two towns to enable continued operations. Based on a two-step thematic data analysis, our results illustrate that the controller is an essential actor in strategic capital investment projects with high degrees of uncertainty and multiple decision-participants. By using the pragmatic constructivist framework we find that gap-bridging between multiple decision-participants is an essential role for controller, in order to create successful investment proposals. The case study further illustrates that controllers need to learn to speak technical and operational language and to become knowledgeable about business operations to gain trust in order create a functioning construct causality. Our study provides an actor-focused understanding of the organizational and managerial processes within strategic capital investment projects, illustrating how the controller contributes to construct causality therein.