Core competence as a concept has been implemented and studied within the for-profit sector for some decades. The concept is used to understand, develop and sustain competitive advantage and, in contrast to purely market oriented strategies, takeoff from the internal unique strengths within organizations. There exists almost no research on or use of the core competence concept within the non-profit sector. However leaders and decision-makers at non-profit organizations are also challenged to develop their organizations, either to be relevant for its target group or to compete for funding. Doing this without renouncing on the mission and core values requires appropriate strategies and a well-developed compass. The concept of core competence is anticipated to contribute to such processes. This thesis sets out to study whether the concept of core competence can be identified within the sector, and if so, how it can be described and how it is linked to associated concepts, and particularly, how the model for this proposed by Ljungquist (2008, 2010) can be applied. The thesis also explores how the concept of core competence is linked to non-profit sector specific characteristics, more specifically in what way core competence is related to the mission of the organization and how resources unique to non-profit organizations like members, volunteers and supporters possibly contribute to core competence. Finally, the notion of a special added value (Weerawardena and Mort, 2001; Wijkström and Malmborg, 2005) among NPOs will be discussed in relation to core competence as defined by the NPOs included in this paper. The thesis is based on a multiple-case study that includes two national organizations in Sweden and two local organizations in Canada. Findings indicate that core competence exists within the four organizations and that it is linked to each organization’s mission. Also, it is indicated that resources are linked not only by its utilization of, but also by its contribution, to core competence. In other aspects, core competence and its associated concepts identified concur with models developed for the for-profit sector. The characteristics of support mechanisms, like systems, routines, capacities and communication are similar as well as other competencies that have the characteristics of development and adaptation.