Cross-border migration touches upon the core of state sovereignty. As a consequence, states have been very reluctant to delegate authority to the global level in this issue area and no international organisation with a mandate to govern global migration exists. Instead, a plethora of public and private global actors contribute to the governance of human mobility. The central research question this project addresses is how global migration governance is shaped and implemented by this multitude of actors. In order to do so, it intends to provide a political sociology of the involved global migration organisations. This project understands these organisations as a linked institutional ecology with porous organisational boundaries and examines the different practitioners within in, who make global migration governance in their daily practices. By choosing a sociological perspective to approach the question of how global migration governance works and emerges, it differs from existing International Relations research on global migration governance which either focuses on its institutional or discursive dimension. The primary methodological tool this project employs is an institutional ethnography. To be more precise, it ethnographically studies the border professionals at the European external border between Greece and Turkey by conducting a participatory observation on the island of Chios. In addition, it conducts semi-structured expert interviews with staff from UNHCR, IOM, ICMDP and FRONTEX, who are charged with capacity-building and professional training. The general aim of the fieldwork is to reconstruct the professional practices and the explicit and tacit knowledge border professional deploy and consider necessary for performing the task of global border management in order to uncover how global migration governance is made in practice. It looks at border management in particular since it considers it a central dimension of migration governance which epitomises its main rationales and procedures in a very condensed fashion.