On Saint Patrick’s Day, the color you wear actually depends on your religious affiliation.

On this Saint Patrick’s Day, you are likely to take part in that time-honored tradition of wearing green. If not, you risk punishment by pinch, an especially popular custom on schoolyards and around office water coolers. Thus, wearing green on Saint Patrick’s Day is not only widely practiced, it’s virtually required. It’s hard to imagine the holiday without green.

But for a growing number of people, taking part in the holiday means wearing orange. According to this increasingly popular tradition, Protestants wear orange and leave green attire to Catholics. Thus, the color you wear actually depends on your religious affiliation. While this color tradition is not well known, it has deep roots in Irish history.

Protestant Irish have been known as “orange” ever since 1690, when William of Orange (William III), the king of England, Scotland, and Ireland, defeated King James II, a Roman Catholic, in the Battle of the Boyne near Dublin. King William’s victory would ensure Protestant dominance on the island, and has been a source of tension ever since.

‘Orange Protestants’ have been around for quite a while, but wearing the color on Saint Patrick’s is a relatively new phenomenon.

Although the “Orange” in William’s name actually referred to a province in southern France, the color reference stuck. This is why orange now appears in the Irish flag — to symbolize the Protestant minority in Ireland.

Thus, “Orange Protestants” have been around for quite a while, but wearing the color on Saint Patrick’s is a relatively new phenomenon. The first group to take part in the tradition appears to have been the Orange Institution, a Protestant fraternal organization (some might say terrorist organization) more commonly known as the Orange Order. Some members of the order wore orange in various parades on Saint Patrick’s Day as a mark of defiance.

Ironically, Saint Patrick himself would have been surprised by all of the fuss. Patrick wasn’t even Irish; he came to Celtic Ireland as a British missionary. More importantly, Patrick did most of his work in the fifth century, at a time when Christians were simply Christians, long before any division was evident between Roman Catholics and Protestants.

Therefore, Saint Patrick belongs to the whole church, not just Rome, and people of all colors and creeds should take part in the festivities. Yet for some Protestants, part of that fun involves wearing orange. So before the green-wearing Irish among you get into a pinching craze, think twice. Some of us wear orange for a reason.