The knowledge management literature suggests that most communities of practice (CoP) are not adept at sharing what they learn with the larger organization. As a result, organizations experience duplication of effort and ad hoc learning. This organizational problem was examined through an exploratory case study of three CoP in a single organization. One CoP successfully shares what it learns with the larger organization. The question that served as the focus for this study involved understanding the factors that account for knowledge sharing in the successful CoP contrary to expectations and the practices of the two other CoP that were not successful. Knowledge management, learning organization, and organizational culture theories served as the theoretical foundations for the study. Interviews, direct, and indirect observations were triangulated as part of this analysis of the three CoP. Emerging patterns were examined through thematic coding of all data using Creswell's 8-step approach. Results indicated that leaders of CoP can influence knowledge sharing within CoP, relationships among CoP members can be leveraged to influence knowledge sharing with the larger organization, and people who join CoP tend to share what they learn more if their reasons for joining a community of practice are fulfilled. It is recommended that organizations understand where CoP operate in their organization, as they can be utilized as effective tools to engage a corporate-wide knowledge sharing strategy. This study may promote positive social change by improving organizational effectiveness via increased potential for utilizing intellectual capital leading to increased competitive and comparative advantage.