Abstract. [Context and motivation]Outsourcing of software development is an attractive business model. Companies expect cost reduction, enhanced efficiency, and exploited external resources. However, this paradigmatic shift also introduces challenges as stakeholders are spread across distinct organizations. [Question/problem] Requirements traceability supports stakeholders in satisfying information needs about developments and could be a viable way of addressing the challenges of interorganizational development. While requirements traceability has been the subject of significant research efforts, its application across organizational boundaries is a largely unexplored area. [Principal ideas/results] We followed a qualitative research approach. First, we developed a taxonomy identifying the needs of inter-organizational traceability. Second, we conducted semi-structured interviews with informants from 17 companies. Eventually, we applied qualitative content analysis to extract findings that supported and evolved our taxonomy. [Contribution] Practitioners planning and managing inter-organizational relationships can use our findings as a conceptual baseline to effectively leverage traceability in those settings. Effective traceability supports projects in accomplishing their primary goal of maximizing business value.