Punahou School, once known as Oahu College, is a private, co-educational, college preparatory school located in Honolulu CDP, City and County of Honolulu in the U.S. State of Hawaii. With about 3,760 students attending the school, in kindergarten through the twelfth grade, it is the largest independent school in the United States.

Originally founded in 1841, the school has a rich history, a wide variety of programs and many notable alumni. Along with academics and athletics, Punahou offers visual and performing arts programs. In 2006, Punahou School was ranked as the "greenest" school in America. The student body is diverse, with student selection based on both academic and non-academic considerations. In 2008 and 2009, Punahou's sports program was ranked best in the country by Sports Illustrated.

In 1795, the land known as Ka Punahou was taken in battle by King Kamehameha I. Along with Ka Punahou, he gave a total of 225 acres (0.91 km²) of land (from the slope of Round Top down to the current Central Union Church, which included a 77-acre (310,000 m²)-tract of Kewalo Basin) to chief Kameʻeiamoku as a reward for his loyalty. After Kameʻeiamoku died, the land was passed down to his son, Ulumāheihei Hoapili, who lived there for twenty more years. When Hoapili left to become the governor of Maui, he gave the land to his daughter, Kuini Liliha.