For more than 400 years, Lutherans and Reformed were not able to celebrate the Lord’s Supper together due to deep doctrinal conflicts. By signing the Leuenberg Agreement (1973), the Protestant churches were able to overcome the church dividing character of their doctrinal differences and to declare to be in church fellowship with each other. The seminar will analyze the principles of that Agreement and evaluate its strengths and weaknesses and those of the Leuenberg Fellowship of more than 100 churches in Europe (now: Community of Protestant Churches in Europe [CPCE]).