Although a great deal has been written on the Paris Peace Conference, only in recent years have the necessary German documents been available for an analysis of the conference, not only from the Allied viewpoint but also from the German side. One of the great problems faced by the Allied statesmen in 1919 was the territorial conflict between Germany and Poland. The final boundary decisions were much criticized then and in subsequent years, and in 1939 they became the excuse for another world war. In the 1960's, over twenty years after the boundaries established at Versailles ceased to exist, they continued to be subjects of controversy. To understand the nature of this problem, it is necessary to study the factors which influenced the delineation of the German-Polish boundary in 1919. From the conflict of national interests there emerged a compromise boundary which satisfied almost no one. After this boundary was destroyed by another world war, the victors were again faced with the complex task of reconciling conflicting strategic and economic necessities with the principle of self-determination. This time no agreement was possible, and the problem remained a significant factor in German-Polish and East-West relations. The methods by which the statesmen of 1919 arrived at a settlement are pertinent to the unsolved problem of today.