The Treaty of Neuilly was signed, as part of the Paris Conference, on 14/27 November. This settled the disputes and the pending matters between Bulgaria and the Allies.

Earlier, western Thrace was occupied by Greek and French troops. By this treaty Bulgaria renounced all sovereign rights to the territories of western Thrace, which were transferred to the communal control of the Allied Powers. Practically, the way was paved for this area to be eventually adjudged to Greece.

At the same time, a Greco-Bulgarian treaty was signed for voluntary population exchanges between the two countries. The right was granted to minority populations of both sides to choose, according to their national consciousness, the country in which they wished to live. This treaty held sway throughout the 1920s. With the implementation of its terms the Bulgarians of Greek Macedonia and western Thrace departed for Bulgaria, whereas the Greeks of Eastern Rumelia came to Greece. The whole process of migration and the issue of properties in particular was handled by a four-member Mixed Committee.