Thurlby is a village and civil parish in the South Kesteven district of Lincolnshire, England. It is situated just west of the A15 road, 2 miles (3 km) south from the town of Bourne, and on the edge of the Lincolnshire Fens. It is sometimes referred to as Thurlby by Bourne to distinguish it from other villages in Lincolnshire with the same name. Thurlby and the hamlet of Northorpe to its north are conjoined. The parish had a population of 2,136 at the 2001 census, although this had increased by hundreds by the 2011 census, because of a rapid development across the village.