Through my research in the field of international and comparative family law, I pursue two objectives: firstly, the possibility, feasibility and desirability of harmonising, or even unifying, substantive and international family law within Europe; secondly, the extent to which the rules of private international law can designate a law other than substantive national law as the applicable law to govern a cross-border relationship. Both objectives are strongly interconnected. I have carried out research which specifies the ways in which private international law can cooperate with unified and harmonised substantive law in order to meet the needs of international families. Based upon extensive comparative research, I have proposed model laws for Europe in the field of divorce, maintenance, parental responsibilities and property relations between spouses, which can be used by national legislators, the European legislator and courts. My long-standing involvement in international networks provides the opportunity for close collaboration with a large number of prominent family law scholars, not only from Europe, but also from around the world (South-Africa, the United States, Australia, New Zealand and Russia). I am chair of the most important European family law research network, the Commission on European Family Law (www.ceflonline.net). This network was established in 2001 and includes 28 family law experts from 26 European jurisdictions. Within the Utrecht Centre for European Research into Family Law (UCERF), I also coordinate, initiate and supervise inter- and multidisciplinary research in the field of family relations. I frequently cooperate with sociologists, psychologists and economists.