Abstract: References to technology abound in ongoing policy and political debates on the governing of people on the move. In these policy and political debates, the assumption is generally that technology can improve migration governance. The chapter argues that the effects of specific devices, such as biometric identification systems or computerised networks for migration and border enforcement should always be examined as unfolding with socio-technical and techno-political contexts. By critically examining the available literature, the chapter identifies the politics of knowledge, namely the reasoning and knowledge practices underpinning the identification and sorting of persons on the move as the core matter raised by the imbrication of technology and migration governance. The matter at hand is not how technology can improve migration governance, in this respect, but how shifts within socio-technical settings within migration governance and beyond lead to transformations in the way persons on the move are known to governmental authorities, and therefore acted upon.