This thesis is a study of international data privacy cooperation, which has a twofold aim. Firstly, on the empirical level, it investigates the strategies and alternative paradigms for international data privacy cooperation and reveals the potential as well as the limits of different cooperative models. Secondly, on the theoretical level, it relies on a series of analytical constructs from legal and political theory to critically assess various aspects of cooperation and aims to contribute to the further advancement of those methodological frameworks. To accomplish these goals, the thesis adopts a multidisciplinary approach of a newly emerging 'international relations and international law' sub-discipline. Firstly, by relying on rational choice, historical institutionalism and game theory, it examines how different countries have been responding to the continuously evolving data privacy policy challenges, and how these divergent responses created a cooperative stalemate among the leading regulatory states. Secondly, it scrutinizes different approaches to customary international law to explore whether data privacy could be considered a principle of customary international law, which would make the mass-surveillance programmes illegal irrespective of the (non)existence of a binding international data privacy treaty. Then, by relying on international agreement design literature, the thesis explores the different 'hard law dreams' for data privacy and argues that these options are difficult to realize in practice. As an alternative, it adopts a global legal pluralism lens to examine the promise of mutual recognition arrangements; and applies trans-governmental networks theory to see whether data privacy commissioners could improve international cooperation. The thesis suggests that effective international data privacy cooperation requires a certain degree of political commitment from states as well as support from private actors. These preconditions do not currently exist. Persisting uncertainty stemming from lack of effective cooperative structures is more acute than ever in a modern world that has extended far beyond the Orwellian 'Big Brother' to cover the 'Facebook Universe,' 'Google World,' and unimaginable mass-surveillance by the Western governments.