This paper argues that in the context of human activity systems, the concept of purpose is critically important and that giving purpose a central role in the development and management of human activity systems can lead to more flexible, effective and autonomous systems. The systems thinking literature is reviewed in order to consolidate and assess current thinking about purpose. The importance of intrinsic purpose is highlighted. Implications for practice in terms of information systems design are illustrated by contrasting two different approaches to the design of knowledge management systems. An analysis of corporations as purposeful systems highlights some of the benefits of a purposeful systems approach. Directions for future research with a focus on purpose are suggested.