Carlton College began as a school founded by Charles Carlton in Kentucky Town, Fannin County, in 1866. It was probably the earliest Disciples of Christ school in Texas. It was moved to Bonham in 1867, when a committee acting on behalf of that city expressed interest in Carlton's school as a replacement for the failing Bonham Female Institute. Happy for the opportunity to increase the size of his school and establish a church, Carlton opened the coeducational Bonham Seminary in the institute's former building in September 1867. The school offered a Christian education for primary, preparatory, and collegiate students. Carlton, his second wife Sally, and two of his daughters were the mainstays of the teaching staff throughout the school's tenure in Bonham. Other teachers joined the staff as time and finances allowed. Carlton's son Charles was the school's vice president from 1875 to 1907. Courses were offered in mathematics and surveying, music, astronomy, physics, botany, chemistry, and geology. Latin, French, English, and two courses in Bible were also offered. No deserving student was ever turned away; tuition was paid in goods and labor or even waived as necessity demanded.
In 1881 the school moved into the Christian church for one year while a new building was constructed nearby to house the students. By this time, the name Carlton was deemed so important to the school's identity that its name was changed by charter to Carlton College. The early 1880s saw the school achieve an enrollment of more than 200. Thereafter, the establishment of other Christian schools and the public education system may have contributed to the school's decline. In 1887 the school became a female-only institution. An impressive three-story hall was built in 1895, and the school continued its work despite declining enrollments until Carlton's death in 1902. An arsonist set fire to the college in 1910. In 1914 the institution, under the guidance of C. T. Carlton and his wife, merged with Carr-Burdette College and moved to Sherman for two years. In 1916 the Carltons returned to Bonham, but Carlton College never reopened.