The background of this doctoral thesis is an interest in work achievement over extended time periods in specialized and technology-infused workplaces. Globalization, digitalization and increased focus on customer services are constituent aspects that have been claimed responsible for the current changes in the way work practices and teamwork are organized. In IT helpdesk work, which is the object of study in this thesis, challenges including dissemination of information, keeping up-to-date with technological changes and coordi- nation of people and tasks have been identified as critical. The aim of this thesis is to illuminate how knowing and competence are maintained and shared as participants engage in backstage activities in helpdesk work. The focus is on the nature of the activities that unfolds when employees engage in activities that include interaction as well as artefacts. The empirical material comprises video- and audio-recorded activities of a second-level helpdesk in a large multinational IT provider. Targeted ‘hot spot’ activities are shift changes, quality discussions and introductions of newcomers. Based on a sociocultural perspective, the (re)production of professional practices is understood as continuous negotiations between participants and tools within a situated framework. Methodologically, this implies detailed investigations of authentic activities where interactions and tool use are analysed from the participant’s perspective. Three studies are included in the thesis, each of them provide insights into the organizing of shared knowing and competence. Study One focuses on how tasks and information are communicated between shifts and transformed into workable units and knowledge. Study Two addresses the role of activities specifically arranged for learning and separated from other work tasks. In Study Three, the focus is on introductions of newcomers and what can be learned from interactions with experienced participants and technological tools. The analyses show that knowledge work is a continuous and communicatively-based undertaking. Continuity across shifts relies on several documenting routines and procedures, but shift change meetings provide opportunities for interpretation and negotiation of information as well as coordination of tasks. Talking about work provides a space for reflection and reformulation of team-related quality norms and values as shared foundations for work. Furthermore, inducting newcomers to the specialized and situated practice brings about the very detailed procedures involved in managing everyday work and technological tools. By describing the reasoning and knowing displayed by helpdesk employees, the thesis contributes to discussions about knowledge work and sharing in organizational settings, teamwork, system design and lifelong learning. To conclude, it is suggested that sharing and reproduction of knowing in practice is a collective effort that entails creative involvement by members of the practice.