Since 1999 Tadcaster has been twinned with the French town of Saint-Chély-d'Apcher, which is in the department of Lozère in the south of France.

Saint-Chély-d'Apcher lies at an altitude of 935 metres in the Massif Central uplands, and is situated close to the main north-south motorway from Paris to Montpellier. It is a lively self-contained town, about the same size as Tadcaster, with a population of approximately 4,500. First-class further education facilities, including a college for catering and hotel management, and a modern steel works, mean the town has a thriving economy.

The town's inhabitants are called Barrabans. This name was allotted to the people of Saint Chély during the Hundred Years' War. In 1363 the town was attacked by the English. The inhabitants defended themselves with bars, and advanced towards the attacking English army to the cry of "barres en avant" ("bars ahead"). The Occitan word 'barraban' means 'rascal', so this nickname has a double meaning.

The Twinning of Tadcaster and Saint-Chély-d'Apcher exists to strengthen cultural ties and facilitate exchange visits of groups and individuals between the two towns and their surrounding areas. In recent years, students from Tadcaster Grammar School have enjoyed visits to Saint-Chély to gain work experience, and this has helped with their language studies.

Over the years the following have been involved in visits between the two towns: scouts, brass bands, swimmers, fire cadets, walking groups, Tadcaster Theatre Company, a dancing troupe, and school students. There have been many other visits involving individuals and small groups.