This thesis sets out to explore the role(s) of UX in the development and establishment of information infrastructure in DMC, a Danish pharmaceutical company. UX professionals constitute an important link between technology and users, yet the prevalent framing of UX work seems to reduce it to a straightforward, mechanical, and uncomplicated endeavor. With infrastructure studies as our analytical lens, we challenge this impression and examine more closely the infrastructuring work carried out by UX professionals as they contribute to the complex socio-technical task of cultivating working infrastructures. Conceptualizing infrastructure as a complex actor-network encompassing a plethora of heterogenous actors, the thesis employs the notion of infrastructural inversion to explore the practical-political process of establishing an information infrastructure in DMC and investigates the ‘battles’ taking place in the process. Based on our analysis, we identify four roles enacted by the UX team. First, they act as a rescue team, summoned to repair infrastructural breakdowns. As negotiators, they build and negotiate relations between different configurations of human and non-human actors, often with the aim of helping users appropriate less-than-optimal infrastructure. As strategists, they employ tactics to maximize the impact on their work and intervene in change initiatives to fend off infrastructural crises. Finally, they engage in activist work to establish UX as a ‘golden standard’ in infrastructural change processes. Based on these roles, we argue that UX professionals can act as central change agents in the establishment and cultivation of infrastructure, and we suggest that foregrounding and leveraging these ‘invisible’ modes of infrastructuring work can potentially lead to more effective and inclusive infrastructural change processes.