The Cookes were put in charge of the Chiefs' Children's School. King Kamehameha III selected as students those who would be eligible for the throne based on their family background. Instruction was in English, and all five of the next ruling monarchs were students at the school. A complex of buildings was built to house the Cookes and students in 1840 as it became a boarding school. In 1846 it was renamed the Royal School, and became funded by the government.
In 1849 Cooke worked for Samuel Northrop Castle who had been a ship-mate on the Mary Frazier as secular supply agent for the mission. As the American Board reduced funding for the Hawaii stations, he co-founded Castle & Cooke as a private company in June 1851. Edward Griffin Beckwith (1826–1909) became the next principal of the Royal School, as it opened to students of all races.
Cooke died in Honolulu, March 20, 1871. The company went on to be one of the "Big Five" corporations that dominated the economy of the Territory of Hawaii. Their 7 children were:
Juliette Montague Cooke in 1876
Joseph Platt Cooke was born June 15, 1838, married Harriet Emily Wilder (1842–1904), sister of Samuel Garner Wilder, and died August 29, 1879. Their son also named Joseph Platt Cooke (1870–1918) married Maud Mansfield Baldwin (1872–1961), daughter of Henry Perrine Baldwin, co-founder of Alexander & Baldwin.
Martha Eliza Cooke was born November 21, 1840, married Samuel Thomas Alexander (1836–1904), the other co-founder of Alexander & Baldwin. She died July 6, 1918.
Juliette Montague Cooke was born August 21, 1843, married Joseph Ballard Atherton (1837–1903) in 1865 and died August 25, 1921. Their daughter Mary Atherton Richards (1869–1951) wrote several histories of the family.
Mary Annis Cooke was born November 6, 1846, married Charles Turner (1845–1894), and died in 1920.
^Amos Starr Cooke; Juliette Montague Cooke; Mary Atherton Richards (1987) . Amos Starr Cooke and Juliette Montague Cooke: their autobiographies gleaned from their journals and letters. Daughters of Hawaii. ISBN978-0-938851-03-5.