- January 1st: The euro is introduced as the official currency of 11 European countries.
- February 11th: The Senate of the United States ratifies the Comprehensive Nuclear Test Ban Treaty (CTBT).
- March 24th: NATO begins bombing of Yugoslavia in an attempt to stop the ethnic cleansing of Kosovo by Serbian forces.
- April 20th: The Columbine High School massacre takes place in Colorado, United States, resulting in the deaths of 12 students and 1 teacher.
- July 2nd: Mexico's Institutional Revolutionary Party (PRI) loses control of the lower house of Congress for the first time in its 71-year history.
- September 30th: An earthquake measuring 7.4 on the Richter scale hits Athens, Greece, killing 143 people and causing widespread damage.
- December 31st: The 20th century comes to an end.
