Carre's Grammar School is a selective secondary school for boys in Sleaford, a market town in Lincolnshire, England. Founded on 1 September 1604 by an indenture of Robert Carre, the school was funded by rents from farmland and run by a group of trustees. The indenture restricted the endowment to £20 without accounting for inflation, causing the school to decline during the 18th century and effectively close in 1816.