Clitheroe Royal Grammar School is a co-educational grammar school in the town of Clitheroe in Lancashire, England, formerly an all-boys school. It was founded in 1554 as "The Free Grammar School of King Philip and Queen Mary" "for the education, instruction and learning of boys and young men in grammar; to be and to continue for ever." Clitheroe Royal Grammar School continues to be based on two sites, with the Sixth Form Centre occupying the historic buildings on York Street, and the Main School at the former Girls' Grammar School buildings on Chatburn Road.