- Dec 1 1st skywriting over US-"Hello USA"-by Capt Turner, RAF
- Dec 1 Polish state Chief Marshal Jozef Pilsudski resigns
- Dec 2 CFL Grey Cup, Richardson Stadium, Kingston: Queen's University win first of 3 straight titles; defeat Edmonton Elks, 13-1
- Dec 3 First successful technicolor movie (Tall of the Sea), shown in NYC
- Dec 4 Lucille Atcherson, becomes first woman legation sect-US foreign service
- Dec 6 1st constitution of Irish Free State comes into operation
- Dec 6 1st electric power line commercial carrier in US, Utica, NY
- Dec 9 Gabriel Narutowicz elected Polish president
- Dec 9 15th Women's Australasian Championships (1st for women): Margaret Molesworth beats Esna Boyd (6-3, 10-8)
- Dec 9 15th Australasian Championships: James Anderson beats Gerald Patterson (6-0, 3-6, 3-6, 6-3, 6-2)
- Dec 10 Nobel prizes awarded to Niels Bohr (Physics), Francis William Aston (Chemistry) and Fridtjof Nansen (Peace)
- Dec 10 Pete Henry makes longest known NFL drop-kicked field goal, 45 yards
Nobel Prize
Dec 10 Danish physicist Niels Bohr awarded the Nobel Prize for Physics, for work on the structure of atoms, at a ceremony in Copehagen
Niels Bohr
- Dec 13 Charles Ebbets proposes putting numbers on players' sleeves or caps
- Dec 15 IVVV (association) peace congress on war forms in Hague
- Dec 16 Mutual Association of Eastern Colored Baseball Clubs formally organizes
- Dec 16 NSW all out for 786 against South Australia Cricket
- Dec 17 Last British troops leave Irish Free State
- Dec 19 Theresa Vaughn, 24, confesses in court in Sheffield, England, to being married 61 times over 5 years in 50 cities in three countries
- Dec 20 14 republics form Union of Soviet Socialistic Republics (USSR)
- Dec 20 Polish parliament selects Stanislaw Wojcieckowski as president
- Dec 22 Belgian parliament rejects Dutch university in Ghent
- Dec 23 BBC Radio began daily newscasts
- Dec 23 Pope Pius XI pleas for peace: encyclical Ubi arcano
- Dec 24 BBC broadcasts first British radio play "The Truth about Father Christmas"
- Dec 24 London Coloseum opens
Event of Interest
Vladimir Lenin