The role of organising and disseminating knowledge as a global public good has become a major preoccupation of international development organisations. One area in which they are particularly active is support for microfinance programmes in developing countries. More recently, the microfinance `best practices' deposited in, and disseminated by, these international organisations have been associated with social capital. This paper examines the ways in which the notion of social capital is employed to explain the success of microfinance programmes.