Recent studies confirmed the creation of value by social information systems. However, few is known about the mechanisms that create value in social information systems. Using a design science approach, this article investigates how social information systems create value. Based on a literature review, we identify four types of emergent interactions in social information systems that create value: social production, co-creation, weak ties, and egalitarian decisions. The paper proposes a holistic framework for understanding business value and develops a research agenda to further explore the value creation mechanisms of social information systems.