<p>Self-sovereign identity (SSI) is a novel approach to digital identity management, which is controversially discussed in technological communities and academia and lately also in the political space. Positions in the debate range from touting SSI as introducing a paradigm shift in internet identity and user privacy, while others dismiss the concept as libertarian hyperbole. SSI aims to give individuals an independent digital existence and control over their digital identities. Technically, this is achieved by providing individuals with digital identity wallet applications, which allow them to store and present digitally verifiable credentials. Despite its transformative potential, SSI is not comprehensively conceptualized in information system research. Therefore, in this Fundamentals article, we offer the following contributions: First, based on existing information systems research, we provide a consolidated definition and a conceptual framework of SSI structured along five analytic levels: (1) foundational principles, (2) credential exchange, (3) technical building blocks, (4) applications, and (5) governance. Second, we present an information systems research agenda on SSI, including concrete research questions and promising theoretical directions.</p>