Introduction. The aim of this thesis is to investigate problems that users face when using a library discovery service, and determine which problems can be solved by UX design and which problems must be solved by information literacy teaching. A second aim is to examine how UX specialists and user instruction specialists cooperate and how these two specialties are shaped by each other and by the discovery service. Method. User problems were identified by analyzing documented reference questions from the library support chat. A survey based on the user problems was sent to UX specialists and user instruction specialists. The survey was followed by a focus group interview with the same participants. Survey data and transcripts of the focus group interview formed the data for analysis. Analysis. Qualitative analyses were carried out on the data. Theories on organizational structure and professional specialization formed the basis for analysis. Results. The results imply that UX design can be used to solve problems related to wayfinding and problems that can be solved by providing short on-screen instructions, while information literacy teaching can be used to solve problems that require a wide set of information literacy skills. Conclusion. Users’ successful use of the library discovery service requires information literacy teaching as well as continuous UX assessment and design. In the studied organization, UX specialists and user instruction specialists have found ways to cooperate in providing users with high quality services. For UX to be successful, a ”UX mindset” must be employed by all members of the organization. This is a two years master’s thesis in Library and Information Science.