Knowledge sharing is assumed to be challenging for most organizations. Most of the knowledge management research has hitherto focused on profit driven organizations, leaving the NGO context less attended to. This thesis intends to contribute to science by addressing the barriers to knowledge sharing in a knowledge intensive NGO, where volunteer engagement is confirmed. It applies the practical approach to knowledge sharing, implying that knowledge only can be shared in human interactions. By asking how individual and organizational barriers prevent knowledge sharing and how these affect overall knowledge sharing in the organization, this thesis seeks to deepen the understanding on knowledge sharing in NGOs and knowledge intensive organizations. The thesis uses a qualitative case study, illustrated by the NGO Engineers Without Borders Sweden. Six interviews were conducted, and the results analyzed with a thematic analysis. The analysis resulted in four overarching themes identified as barriers to knowledge sharing: lack of time, lack of internal network structures, lack of leadership and handover challenges. Lack of time, lack of internal network structures and lack of leadership have previously been identified as barriers to knowledge sharing, but this study highlighted new dimensions of the themes. For the theme of time, no correlation was found to trust. Both lack of internal network structures and lack of leadership opened up a question of quality. The newfound theme was handover challenges, which proves a challenge in the volatile volunteer environment, especially if knowledge is only tied to its carrier and impossible to document.