Claim: April Fools' Day began in the 1500s when the Gregorian calendar took over from the Julian. Those who forgot the change and attempted to celebrate New Year's  on the wrong date were teased as "April fools."
Fact-check: The Origins of April Fools' Day
Verdict: legend
Organisation: Snopes
Author: Barbara Mikkelson
Date published: 2000-03-22T01:01:00