- Jan 5 Mao Zedong writes "A Single Spark Can Start a Prairie Fire"
- Mar 12 Mohandas Gandhi begins 200m (300km) march protesting British salt tax
- Mar 13 Clyde Tombaugh announces discovery of Pluto at Lowell Observatory
- Apr 2 Ras Tafari Makonnen becomes Emperor Haile Selassie of Abyssinia (Ethiopia)
- Jun 24 1st radar detection of planes, Anacostia, Washington, D.C.
- Aug 16 1st British Empire Games open in Hamilton, Canada
- Nov 2 Coronation of Ras Tafari Makonnen as Haile Selassie I, 225th Emperor of Ethopian Solmonic Dynasty
- Mar 31 The Motion Pictures Production Code is instituted, imposing strict guidelines on the treatment of sex, crime, religion and violence in film for the next 38 years
- Aug 9 Betty Boop debuts in Max Fleischer's animated cartoon Dizzy Dishes
- Aug 16 The first color sound cartoon, called Fiddlesticks, is made by Ub Iwerks.
- Oct 14 George Gershwin and Ira Gershin's musical "Girl Crazy" starring Ginger Rogers and Ethel Merman premieres in NYC
- Jul 13 1st-ever football (soccer) World Cup competition begins in Uruguay
- Jul 30 1st FIFA World Cup Final: Uruguay beats Argentina 4-2 in the inaugural event in Montevideo, Uruguay
- Dec 12 Baseball Rules Committee greatly revises the rule book, ball bouncing into stands not a HR, now a double
- Dec 16 Golfer Bobby Jones is the first to win the James E. Sullivan Award (best US amateur athlete)
Marguerite Perey discovers francium (Fr), the last naturally occurring element to be found
On January 7, 1930