Adèle Appriou (Migration Policy Institute Europe, Belgium) Adèle Appriou Jasmijn Slootjes (Migration Policy Institute Europe, Belgium) Jasmijn Slootjes Rhea Ravenna Sohst (Migration Policy Institute Europe, Belgium) Rhea Ravenna Sohst University of Krems Press 2025 Key points • Irregular migration data is used to inform decisions across sectors—from service planning and public debate to policy design—but remains poorly aligned with the needs of those expected to use it. This chapter examines how different stakeholders rely on the data, and where gaps emerge. • We introduce the data pathway to show how data on irregular migration are defined, collected, shared, and interpreted. At each stage, competing mandates, vague concepts, and inconsistent practices risk undermining coherence and usability. • Five core challenges, such as gaps in availability, ambiguous definitions and low data literacy, limit the value of the data. Legal and institutional barriers, particularly a lack of knowledge about the implication of the GDPR, further constrain responsible sharing and can erode trust. • Improving data use requires more than technical or methodological improvements. It calls for clearer definitions, accessible documentation, stronger privacy protections, and sustained investment in the capacity of those who collect and use the data. PDFDocument eng 2025-09-30T11:36:03.263497Z 2025-09-30 Data use Stakeholders GDPR Data challenges Policy impact 664701 b application/pdf http://creativecommons.org/licenses/by-nc/4.0/