- May 1 Cyprus becomes a British Crown Colony
Jimmie Foxx MLB Debut
May 1 Future Baseball Hall of Fame catcher Jimmie Foxx makes his MLB debut at 17 for Philadelphia A's; pinch-hits a single in 9-4 loss v Washington
John Scopes Arrested for Teaching Evolution
May 5 Dayton teacher John T. Scopes arrested for teaching evolution in Tennessee
- May 5 Yankee Everett Scott is benched, ending his 1,307-game playing streak
- May 6 Ty Cobb hits his 5th HR in 2 games tying Cap Ansons record of 1884
- May 7 1st projection planetarium opens at Deutsche Museum in Munich, Germany
- May 7 MBA Pittsburgh Pirate shortstop Glenn Wright makes an unassisted triple play
- May 7 Phillies have their 8th game postponed in a row
50th Preakness
May 8 50th Preakness: Clarence Kummer aboard Coventry wins in 1:59
- May 8 French colonial army beats Rifkabylen in Morocco
- May 9 Cornerstone for Hebrew University, Jerusalem, laid
- May 10 To control demonstrations against foreigners, British troops in Shanghai fire into a crowd, leading to a boycott against British goods
- May 11 Communist Party of Holland splits
- May 11 Kara-Kalpak Autonomous Region constituted in RSFSR
- May 12 Uzbekistan & Kirgizistan become autonomous Soviet republics
Mrs Dalloway
May 14 Virginia Woolf's novel "Mrs Dalloway" is published by The Hogarth Press
51st Kentucky Derby
May 16 51st Kentucky Derby: Earl Sande aboard Flying Ebony wins in 2:07.6
Speaker Hits 3,000
May 17 Cleveland Indian Tris Speaker gets his 3,000th hit
- May 21 George Lloyd, Baron Lloyd of Dolobran, becomes British High Commissioner in Egypt
- May 21 Norwegian explorer Roald Amundsun leaves Spitsbergen with 2 seaplanes for the North Pole
- May 26 Future Baseball Hall of Fame center fielder Ty Cobb is first to collect 1,000 extra-base hits when he doubles in Detroit Tigers' 8-1 win against the Chicago White Sox at Comiskey Park
- May 30 British mariners shoot on demonstrators
- May 30 In China protests erupt against the Great Powers infringing on Chinese sovereignty.
- May 30 Indianapolis 500: Race winner Peter DePaolo becomes first driver to complete 500 miles in under 5 hours, and have an average over 100 mph; Norman Batten drives 21 laps of relief while DePaolo has his hands bandaged due to blisters
- May 30 Peter DePaolo became 1st man to average over 100 mph at Indy