27 nations were represented
- Belgium
- Brazil
- Canada (signed under 'British Empire')
- China
- Cuba
- Czechoslovakia
- France
- Greece
- Guatemala
- Haiti
- The Hejaz (later absorbed into Saudi Arabia)
- Honduras
- Italy
- Japan
- Liberia
- Lithuania
- Montenegro
- Nicaragua
- Panama
- Poland
- Portugal
- Romania
- San Marino
- Siam
- United Kingdom
- United States
- Kingdom of Serbs, Croats, and Slovenes (later renamed Yugoslavia)