Cate School is a highly selective university-preparatory school for boarding and day students in grades 9–12 located in Carpinteria, California, eleven miles from Santa Barbara. In 2012, the school had 270 students, who came from 31 states and 18 foreign countries. In 2022, Niche ranked Cate School the best boarding school in California and the 13th-best in the United States.

Cate School was founded in 1910 by Curtis Wolsey Cate, a 25-year-old graduate of Roxbury Latin School and Harvard University. Originally called the Miramar School, its classes were held in the Gane House, a leased private residence in Santa Barbara's Mission Canyon. (The Gane House, would be destroyed in the Jesusita Fire in 2009.) A prep school for boys in grades 7 to 12, its first academic year enrolled 12 students.

In 1911, Cate moved his school to the Stewart Walcott Ranch in the Carpinteria Valley and renamed it the Santa Barbara School (or SBS). The extra space allowed him to pursue a program he had admired in his year of teaching English at the nearby Thacher School: each student was given a horse to care for, and much of the school's early campus and activities were based on horseback riding. Cate would later write, "The horse was as much a part of our lives as the book. Afternoons, mounted for a canter before baseball or for practice on the gymkhana field; Saturdays and Sunday, off for long rides or camping…learning from nature and the care of an animal larger than one's self, lessons not taught in the classrooms."

In its early years, the school's buildings lacked heat, hot water, or electricity. SBS's first graduate was Dohrmann Pischel in 1914.

In 1914, Cate accepted Walcott's offer to sell his 150-acre "mesa property", a former ostrich farm. The school moved immediately to the southwest mesa slopes, and then again in 1929 to its current location atop a hill within the property near the Santa Ynez Mountains. The first permanent campus buildings on the Cate Mesa were designed between 1928 and 1929 by architect Reginald Davis Johnson, son of the school's first president of the board of trustees, Episcopal bishop Joseph Horsfall Johnson. Campus buildings have since been designed in keeping with Johnson's original Monterey Colonial style.

Cate's total enrollment had increased to 40 in 1919, and the school finally had enough boys to field athletic teams to compete with other private schools in the area. The first and most obvious of these was the Thacher School, which would become the traditional arch-rivalry of both schools. Cate and Thacher competed in baseball in Cate's first academic year despite the former's meager enrollment, and Cate lost the game 60-4. Cate recorded its first win in baseball over Thacher in 1921 thanks to the surge of enrollment following World War I. Perhaps the most important competitive event between the two schools, however, was gymkhana. Gymkhana, an equestrian event, involved a multitude of events such as picking up an orange or a sack on a turn at a dead run, tilting at rings, sprints, and relays. In contrast to their shortcomings on the baseball field, Cate posted an all-time winning record of 15-9 over Thacher in the 24 gymkhana competitions held. The geographic locations of Cate and Thacher, their eventual status as the two premier boarding schools of the west, and the competitiveness of their early baseball and equestrian competitions likely contributed to the rivalry as it stands today over 100 years later.

The Great Depression and World War II brought economic hardship and declining enrollment. Curtis Cate was forced to cut costs. The school's official colors changed from purple and silver to blue and white due to dye shortages. In 1942, the school ended its distinctive horse program. To replace the hard work and responsibility the horse program was meant to provide, Mr. Cate initiated the "Work Program", which required each boy to contribute six hours of labor to the school's community each week, which alumnus Barnaby Conrad '40 said could be "everything from road building and bricklaying to plumbing, gardening and the raising of farm animals." Daily chores remain a responsibility for all Cate students, with only seniors being exempt.

The Santa Barbara School was renamed the Cate School to honor the headmaster upon his retirement in 1950.