Collecting and processing large volumes of both personal and non-personal data on migrants and displaced populations is an integral part of IOM’s work. Through the ongoing expansion of its primary data collection mechanism, the Displacement Tracking Matrix (DTM), the organization has come to be the most widely-used and authoritative source of data on internal displacement in particular. This chapter outlines how IOM has positioned itself in an increasingly competitive market of migration and displacement data and discusses the normative obligations that come with this. An analysis of the use of DTM in Haiti and along migratory routes in West and Central Africa illustrates that apart from its key role in the humanitarian planning cycle, one important political function of the DTM has been to showcase the success of donors’ policy interventions. This goes hand in hand with a number of risks and pathologies like the statistical “erasure” of populations with enduring needs and the crowding out of more development-oriented data collectors that raise questions with regard to IOM’s adherence to the principle of data responsibility. Against this background, the chapter calls for a change in institutional set-up and funding structure to ensure that IOM engages in responsible data collection only.