As on 1 January 2020, some three percent of the population of the EU were citizens of one member state living and/or working in the territory of a member state other than that of which they are a citizen. In addition, around five percent of the resident population of the EU consisted of third country nationals. Naturally, these diasporic groups formed cross-border couples consisting of partners of different nationalities or partners of the same nationality both living in a country other than that of their origin. This reality, to be sure, raises many legal questions for the persons involved where the national family laws of several countries come into play. In an effort to bring about added legal certainty and predictability to couples in cross-border situations, the EU adopted several instruments often referred to together as 'EU private international family law'. This volume examines the two most recent of these: the Matrimonial Property Regulation (Regulation (EU) 2016/1103) and the Regulation on the Property Consequences of Registered Partnerships (Regulation (EU) 2016/1104), together referred to as the 'Twin Regulations'. These have proved to be a crucial piece of the European family law puzzle, regulating aspects of the everyday lives of those concerned. This book presents an in-depth analysis of these instruments, revealing the substance of the provisions in the regulations and exploring their practical implications in EU family law by discussing questions that are closely related to matrimonial and partnership property regimes. The contributors also cover the relevant CJEU case law and, where available, the national case law of the EU countries. Case studies are used to interrogate the potentialities of these new instruments. This book is a significant contribution to the literature on private international family law in general and on EU matrimonial property regimes in particular. It is addressed to legal professionals as well as academics and law students.