This paper describes a program of research designed to understand how knowledge-sharing and learning can be supported in virtual communities. To conduct this research, we propose the development of a series of knowledge sharing tools and procedures followed by a rigorous evaluation of the use of these tools in real virtual community environments. The paper starts with a brief examination of relevant theory in knowledge management and learning. This leads to a comprehensive set of research questions. To investigate these questions, we next propose a set of tools for supporting collaboration, knowledge sharing and learning for distributed communities. Evaluation is also a vital element of this research.