Wallonia (French Wallonie), administrative and language region in southern Belgium, consisting of five provinces: Liège, Luxembourg, Namur, Hainaut, and Walloon Brabant. The region is bordered by France to the south and west, Germany and Luxembourg to the east, and the Belgian region of Flanders to the north. The northern part of Wallonia consists of low plateaus, dissected by tributaries of the Meuse River in the east and the Schelde River (also called the Escaut) in the west. The southeast is dominated by the more rugged topography of the Ardennes, with an average elevation of about 400 m (about 1,300 ft). Beyond the Ardennes, in the far southern part of Wallonia, is a region of low hills known as the Belgian Lorraine. Much of the area of the Ardennes and Belgian Lorraine has coniferous forests at high elevations and mixed coniferous and deciduous forests at lower elevations. Wallonia's major rivers include the Meuse, the Sambre, the Ourthe, and the Semois; the Meuse is a major tributary of the Rhine River.

The capital city of Wallonia is Namur, located in the central part of the region. Other major cities include Mons, Charleroi, and Liège. The city of Tournai is important for its history and outstanding architecture. Wallonia is inhabited predominantly by a French-speaking people known as Walloons. There is also a small German-speaking minority that lives on the eastern edge of the region, in the districts of Eupen-et-Malmédy, and Saint Vith. The inhabitants of these districts, which were acquired from Germany after World War I (1914-1918), comprise less than 1 percent of the Belgian population.

Agriculture is important economically in northern Wallonia, particularly the cultivation of cereal grains, potatoes, and other vegetables, while the Ardennes uplands are devoted to grazing and forestry. Wallonia's Sambre-Meuse Valley was the first place in continental Europe to experience the Industrial Revolution, in the first half of the 19th century. The coal mines, iron and steel mills, chemical plants, and textile factories of the region were the foundation of Belgium's economy in the late 19th and early 20th centuries. Changing economic patterns, including the exhaustion of accessible coal deposits, led to the decline of Walloon industrial competitiveness in the latter half of the 20th century. Growth in the service sector and the establishment of specialized metallurgical and mechanical industries have alleviated the economic hardships to some degree, but Wallonia's economic significance in Belgium is now overshadowed by the Flanders region to the north. In recent decades, tourism has begun to play a more important economic role in Wallonia, particularly in the Ardennes.

The Walloons have inhabited the region now known as Wallonia for thousands of years, descending from an ancient Celtic people known as the Wala. Economic decline in Wallonia in the 20th century was accompanied by Flemish growth, especially in the textile industry, and tensions between the Walloons and the Flemish grew. In response to disputes over language rights in Belgium, Walloon activists began promoting the notion of Wallonia as a distinct political entity within the country. These people were separated from the Flemings of the north by a heavily forested region that divided what is now the country of Belgium. Wallonia was not recognized as a region until the early 1960s, when Belgium was partitioned along historic language lines (with the exception of the city and suburbs of Brussels, which remained bilingual). Between 1970 and 1993 constitutional revisions transformed Belgium into a federal state with primary power resting in Wallonia and the other two administrative regions, Flanders and Brussels. Wallonia is governed by a regional council that consists of members of the Belgium parliament directly elected from Wallonia. Area, 16,844 sq km (6,504 sq mi); population 3,435,879 (2007 estimate).