The topic of this thesis is how computer applications can support knowledge sharing between individuals in an organization. The thesis particularly focuses on solutions that facilitate for people to find other persons to share knowledge with, rather than solutions where information is stored in some kind of database for the purpose of being reused by other persons. The thesis describes one shorter and one longer ethnographic study about information and knowledge sharing in two different settings. The studies have shown that what actions people take when they search for information and knowledge depends on the problem itself, and on the situation in which the problem occurs. The results from the studies indicate that supporting people in knowing about others’ activities and availability would be more important when supporting knowledge sharing, than a specific knowledge system with the purpose of storing information to be reused as knowledge. This awareness can be supported in a number of different ways, some based on social activities, and some based on technical solutions. Social activities involve supporting the development of social networks, communities of practice, and other kinds of social activities that facilitate for people to get to know each other and get an opportunity to talk to each other. There exists many technologies that can support people’s knowledge about others’ activities and availability. Awareness systems focus on collecting and presenting information about, for example, where a person is located and how busy a person is. Some awareness systems collect such information automatically using, for example, sensor technology or electronic calendars, while others require the user to enter the information by him- or herself. It is more difficult to get the second kind of systems to work in practice because it requires that the time a user spends on supporting the system is also returning a benefit in the end. Ordinary information systems may also contribute to supporting people’s knowledge about others’ activities and availability, but they need to be structured and searchable in a way that fulfils this purpose. Also, there usually exist more than one documentation repository in an organization among which some may be structured and some not. Based on the studies that have been conducted a number of prototypes supporting knowledge sharing have been developed and evaluated. The technologies focused on are notification systems including mobile solutions to communicate with others, awareness systems focusing on activities and availability, and information management to make already existing written documentation structured and searchable. These prototypes have been evaluated using video recorded scenarios, based on the studies conducted, and focus groups in a medium sized consultancy organization. The results from the evaluation show that the suggested prototypes in the large fulfil the purpose of supporting knowledge sharing in an organization. Based on the three field studies conducted within the work of this thesis, a framework for supporting knowledge sharing through computer support is suggested. The framework focuses on issues such as annoying interruptions, platform independent communication, privacy aspects, and how the information can be presented. / QC 20100609