City Montessori School (CMS) is a co-educational English medium private school, which provides pre-school education up to K-12 (Grade 12) level in Lucknow, India. The school was founded in 1959 by Dr. Bharti Gandhi and Dr. Jagdish Gandhi. It is cited by the Guinness Book of World Records as the largest school in the world, reporting 64,547 students by 2020. CMS has 21 branches in Lucknow alone. CMS is affiliated with the Council for the Indian School Certificate Examination and Cambridge Assessment International Education (CAIE).