On the 17th of May 2017 lawyers from Poland and Spain met in Warsaw at the International Symposium titled “Separation and cooperation between State and Church in Europe: The case of Polish and Spanish law”. It was organized by the Faculty of Canon Law of the Cardinal Stefan Wyszyński University of Warsaw. The main issues discussed at the conference concerned church-state relations in modern Europe, especially the constitutional principles and specific legal regulations in Poland and Spain. The programme included eight key lectures on the historical development of the concept of separation between church and state, some theoretical models of church-state relations and the differences between concept of a secular state and a religiously neutral state. Other lectures dealt with the role of concordats in the modern world, practical problems of interpreting and implementing the principle of autonomy and independence of religious denominations, as well as meaning of bilateral church-state agreements in the Polish and the Spanish system of law.