Since 600 BC present-day Belgium is inhabited by Celtic tribes, like the Belgae. Between 57 and 51 BC the Belgae are defeated by the Roman Empire. The area becomes the Roman province of Belgica and is romanized. Around 256 the Germanic tribe of the Franks enter Belgica and since 296 they rule the area as defender of the border of the Roman Empire. This culminates in the forming of the Frankish Realm. The northern part of present-day becomes a Germanic speaking area, whereas the south remains a Romanic speaking area. The Frankish Realm becomes an independent state, but in 639 the country is divided in Austrasia and Neustria. Both kingdoms are reunited in 719.

At a new division of the Frankish Empire in 843, Belgium becomes mainly part of the Middle Frankish Empire. In 925 the area is annexed to the Eastern Frankish Empire, later continued by the German Empire. Only the western part becomes part of the Western Frankish Kingdom, later continued by the France. In the feudal German Empire and France the duchies and counties, together known as the Netherlands, come between 1384 and 1451 under the rule of Burgundy, continued by Habsburgians since 1506. The bishop-principality of Liege remains separate.

After the division of the Habsburgian countries in 1555 the Netherlands come under control of Habsburg-ruled Spain. In 1568 a rebellion against the Spanish occupation starts and the northern part of the Netherlands develop as the Republic of the United Netherlands into a de facto independent state. The southern parts remain at the same time under Spanish rule as the Spanish Netherlands. In 1713 the Spanish Netherlands are acquired by Austria: the area gets known as the Austrian Netherlands. After a revolution in 1789 the United Belgian States are founded, but already in 1790 Austrian rule is restored. In 1794 France invades the Austrian Netherlands and incorporate them together with Liege into France.

After the French defeat in 1815, the Austrian Netherlands are united with the Netherlands and Liege into the Kingdom of the Netherlands. This is a constitutional monarchy with real power in hands of the King.

A revolution in the Southern Netherlands brings in 1831 the seccesion from the Netherlands as the Kingdom of Belgium. Belgium becomes a constitutional monarchy. In 1847 the Parti Libéral (Liberal Party, PL) comes to power. Liberal rule ends in 1870, when the Parti Catholique (Catholic Party, PC) wins the elections. Between 1878 and 1884 the PL is in power again, but after the elections of 1884 the catholics can dominate the government for more then 30 years. The catholic governments introduces universal male suffrage in 1893 and emancipates the Dutch language as the second official language in 1898. Between 1914 and 1918 large parts of Belgium are occupied by Germany. Universal suffrage is introduced in 1919. The first elections under this system lead to a victory of the Parti Libéral/Liberale Partij and the Parti Ouvrier Belge/Belgische Werkliedenpartij (Belgian Workers' Party, POB/BWP). The Katholieke Verbond van België/Union Catholique Belge (Belgian Catholic Union, KVB/UCB) remains dominant and is part of all governments until 1940, mostly in coalition with the LP/PL. Prime ministers are Léon Delacroix (1918-1920), Henri Carton de Wiart (1920-1921), Georges Theunis (1921-1925 and 1934-1935), Aloys, burgrave van de Vyvere (1925), Prosper, vicomte Poullet (1925-1926), Henri Jaspar (1926-1931), Jules Renkin (1931-1932), harles, comte de Broqueville (1932-1934) and Paul van Zeeland (1935-1937). In 1937 Paul Emile Janson of the LP/PL becomes prime minister and in 1938 he is succeeded by Paul-Henri Spaak of the POB/BWP. The catholics regain the premiership in 1939 with Hubert Pierlot. In 1940 Belgium is invaded and occupied by Germany. Pierlot and his government go into exile in London.

After the liberation in 1944 Achille van Acker can form a coalition in 1945 of his Socialistische Partij/Parti Socialiste (Socialist Party, SP) with the LP. In 1946 he is succeeded by Camille Huysmans. From 1947 on the SP governs in coalition with the Christelijke Volkspartij/Parti Social Chrétien (Christian People's Party, CVP) under Paul Henri Spaak. In 1948 women are granted the right to vote. Spaak is succeeded in 1950 by Jean Duvieusart (CVP) and Joseph Pholien (CVP), in 1952 by Jean van Houtte (CVP). In 1954 the SP and the LP form a new coalition under Achille van Acker. Belgium is a co-founder of the European Communities in 1957 (renamed European Union in 1993). Between 1958 and 1961 the christian-democrats and the liberals govern under Gaston Eyskens, followed in 1961 by the christian-democrats and the socialists under Théodore Lefèvre.

In 1962 Belgium is formally divided in two linguistic parts. Gradually Belgium devolves in the upcoming decades into a federal state. Lefèvre is succeeded in 1966 by Pierre Harmel. The christian-democrats remain dominant and form coalitions with the liberals under Paul Vanden Boeynants in 1966, the socialists under Gaston Eyskens in 1968 and the liberals under Gaston Eyskens in 1972. Edmond Leburton becomes prime minister in a coalition of socialists, christian-democrats and liberals in 1973. But already in 1974 the christian democrat Leo Tindemans forms a coalition with the liberals. In 1977 he forms a coalition with the socialists. Two years later Paul Vanden Boeynants becomes prime minister. In the meantime the national parties have split into Flemish and Walloon parties.

In 1979 Wilfried Martens of the Christelijke Volkspartij (Christian People's Party, CVP) becomes prime minister in a coalition with the socialists. When a coalition with the liberals is formed in 1981 he is succeeded by Mark Eyskens, but he resumes office in this coalition in 1981. Further changes of the constitution were realized in 1988-1989. In 1992 Martens is succeeded as prime minister in this coalition by Jean-Luc Dehaene.

Another important constitutional reform occurrs in the summer of 1993, changing Belgium definitively from a unitary to a federal state. This makes Belgium is a federation of Dutch-speaking Flanders, francophone Wallonia and bilingual Brussels. In 1999 the liberal parties win the parliamentary elections and Guy Verhofstadt of the Vlaamse Liberalen en Democraten (Flemish Liberals and Democrats, VLD) becomes prime minister in a coalition of the liberal and socialist parties. This is continued after the elections in 2003.