Castellserà is a village in the province of Lleida, in the autonomous community of Catalonia, Spain. It is located in the western part of Catalonia, within the comarca of Urgell, in the fertile plains of the Segre river basin.
The village has a population of 993. Like many settlements in this part of Lleida, it is a small, rural municipality whose economy has traditionally been tied to agriculture, particularly the cultivation of cereals, fruit and other crops typical of the surrounding irrigated lowlands.
Castellserà is one of a number of small municipalities that make up the comarca of Urgell, a district centred on the town of Tàrrega. The area is known for its flat, agricultural landscape and its network of historic villages, of which Castellserà is one.