City Montessori School (CMS) is a co-educational English medium private school that offers education from Pre-school 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 mentioned as world's largest school by Guinness Book of World Records which reported 55,547 students as of 2019. In 2014, CMS society was accredited with the United Nations Department of Public Information as affiliated NGO.