Eure-et-Loir (French pronunciation: [œʁ‿e lwaʁ], locally: [øʁ‿e lwaʁ]) is a French department, named after the Eure and Loir rivers. It is located in the region of Centre-Val de Loire. In 2019, Eure-et-Loir had a population of 431,575.

Eure-et-Loir is one of the original 83 departments created during the French Revolution on March 4, 1790 pursuant to the Act of December 22, 1789. It was created mainly from parts of the former provinces of Orléanais (Beauce) and Maine (Perche), but also parts of Île-de-France (Drouais, Thymerais, Valley of the Avre, Hurepoix).

The current department corresponds to the central part of the land of the Carnutes who had their capital at Autricum (Chartres). The Carnutes are known for their commitment, real or imagined, to the ancient Druidic religion. In the north of the department another pre-Roman people, the little-known Durocasses, had their capital at Dreux.

Eure-et-Loir comprises the main part of the region of Beauce, politically it belongs to the current region of Centre-Val de Loire and is surrounded by the departments of Loir-et-Cher, Loiret, Essonne, Yvelines, Eure, Orne, and Sarthe.

The most populous commune is Chartres, the prefecture. As of 2019, there are 6 communes with more than 10,000 inhabitants:

The inhabitants of the department are called Euréliens.

The Eure-et-Loir is a department of agricultural tradition (Beauce), but also at the forefront in three economic sectors :

The department is a major economic player in the production of grain and oilseed in France. Its agricultural economy is still heavily dependent on the economic and regulatory environment of the markets for crops. The Eure-et-Loir region is the first grain producer of France. It is also the national leader in the production of rapeseed and peas. Wheat production is by far the most dominant in the area. Nearly 40% of all farmland is devoted to the cultivation of wheat, which has generated an average of 29% of the commercial agricultural production of the department over the last 5 years.