The optional matrimonial property regime of the community of accrued gains was created to address legal difficulties that may arise from marriages between persons of different nationalities or persons not living in their country of origin. It is the result of a treaty between France and Germany and entered into force in 2013. As it approaches cross-border conflicts using substantive legal rules, it has a unique character and is considered to be the first step towards the harmonisation of European family law. It is of interest beyond the borders of France and Germany because other Member States of the European Union can accede to the treaty. Further, the optional matrimonial property regime is open not only to marriages between French and German nationals but also to French or German couples living abroad or foreign couples living in France or Germany. To make the Franco-German treaty more accessible to the lawyer in Europe, this book contains the optional matrimonial property regime in five languages, namely German and French - the official languages - and English, Italian and Spanish. Each article of the optional matrimonial property regime is accompanied by a short commentary. Moreover, to provide the reader with additional background information, translations of the memoranda and explanatory reports are also included. With an introduction by Professor Maria Giovanna Cubeddu Wiedemann (University of Trieste) and Professor Dr. Dr. h.c. mult. Dieter Henrich (University of Regensburg) and translations by Professor Marella Magris (University of Trieste) and Professor Helena Lozano (University of Trieste).