In this chapter we are interested in how public research organizations address internationalisation pressures and Europeanisation dynamics. Whereas internationalisation of research (with a focus on individual research collaboration and, more recently, on researcher mobility) has been widely analysed, we do not know that much about internationalisation processes and strategies at the organizational level of research institutes. And while public research organizations have traditionally been considered as very responsive to national governments’ demands, despite their relevance in terms of public expenditure, no significant efforts have been made to better understand the impact of the European research policy and the emergence of a new space for research on the functioning, structures and strategies of these organizations. A starting point in this chapter is that the conditions under which organizational actors engage and invest resources in international activities are dependent on the structure of the public science system as well as on the organizational features of the public research organizations themselves. In this chapter we will try to build an analytical framework to provide a better understanding of the role of key organizational attributes of public research organizations in the internationalisation process.