This is a calendar of events and festivals in the month of May.
- May 1: May Day or Labor Day, worldwide
- May 3: Polish Constitution Day. The most important holiday in Poland, and on the weekend following the holiday, there are colorful parades in cities with large populations of people of Polish ancestry (such as Chicago).
- May 5: Coronation Day is a public holiday in Thailand
- May 5: Children's Day (子供の日 Kodomo no hi), also known as Boys' Day (端午の節句 Tango no Sekku), Japan
- Until May 5: Golden Week in Japan, an extremely popular time to travel — best avoided as transport and accommodations are often booked solid
- May 6: international blood donation and free eye check up day worldwide