St. Patrick's Day A St. Patrick's Day parade in New York City, 2017. (more) Why Do We Wear Green on St. Patrick’s Day? Written by Melissa Petruzzello Melissa Petruzzello (she/her) is Assistant Managing Editor and covers plants, algae, fungi, insects, spiders, renewable energy and environmental engineering. She also handles certain topics in Christianity,... Melissa Petruzzello Fact-checked by Britannica Editors Encyclopaedia Britannica's editors oversee subject areas in which they have extensive knowledge, whether from years of experience gained by working on that content or via study for an advanced degree.... Britannica Editors Last updated Mar. 11, 2026 •History Every March 17, people in Ireland and around the world suddenly turn green. Shirts, hats, beads, and even rivers take on the color as part of the lively celebration of St. Patrick’s Day. This playful tradition—often called the “wearing of the green”—has become one of the most recognizable customs of the holiday. Yet the connection between St. Patrick, the patron saint of Ireland, and the color green is not as old as many people might...

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