Collegiate is divided into Lower School (Kindergarten-Grade 4), Middle School (Grades 5-8), and Upper School (Grades 9-12). Each division has its own administrative head and core faculty. Many faculty members teach in more than one division of the school. The students and faculty enjoy the advantages of a small-school environment while benefiting from the stimulation a college preparatory school can provide. The atmosphere at Collegiate is shaped by the close interaction of the student body and a sense of community within the school.
Collegiate is a founding member of Interschool, a consortium of eight independent schools working cooperatively to develop programs and activities involving students and teachers from the participating schools. Programs sponsored by Interschool include an annual College Night for juniors and their parents, the tenth-grade trip to Frost Valley, and meetings of special-interest groups to exchange ideas and organize events. The Interschool member schools are Brearley, Browning, Chapin, Collegiate, Dalton, Nightingale-Bamford, Spence, and Trinity.