Libertarian socialism in Belgium never got many chances. In the 19th century it gained some ground within the workers' movement. Radical intellectuals who supported the poor were much influenced by the ideas of Pierre-Joseph Proudhon. Workers and farmers also got the support of anarchists active in the First International. The historian Jan Moulaert has done much to get the story of the anarchists in the Belgium of the 19th century much known.
The Social democrats gave a boost to alternative economy in cities like Gent, they had the money for it. And because of this, the libertarian left became marginal again. At the beginning of the 20th century, anarcho-communism and the libertarian left were gaining ground in Mechelen, a city not far from the capital Brussels. This gave hope to the movement in the Dutch speaking part of the country (the north), anarchism mostly had been happening in the French speaking part of the country. But two World Wars virtually destroyed the movement in Belgium.
The counterculture of the sixties made anarchic tendencies influential again. One of the people responsible for that was Hem Day (picture), an anarcho-pacifist and a friend of the Spanish anarchist leader Buenaventuri Durruti.
A famous writer called Louis Paul Boon started to sympathize a lot with anarcho-syndicalism. Other anarchists were active with actions against militarism in the seventies, like refusing military service, and in the nineties also more and more with squatting and ecological direct actions.
A journal called Alternative libertaire received many readers in Belgium and France. Cities like Liège, Brussels and Gent attracted many anarchists and other radicals to be active in.
Philosophers like Leo Apostel, a libertarian marxist, and Roger Jacobs did much to infuse the movement with social theory. Jacobs also did a lot to get Murray Bookchin more known in Belgium and the Netherlands.
In Belgium, the libertarian left of the 21st century could be described as a movement in which the ideologies of those active in its main center, the Anarchist Center in a big city called Gent, are very important. This place is in the north of Belgium, not far from the border with The Netherlands.
What is the Anarchist Center? In their own words... "The Anarchistisch Centrum is a meeting place for individuals and groups active in Gent with anarchism and/or direct action. Anarchism means for us that we want to work in an anti-authoritarian way at an ecological society in which all power is equally divided." Ideas are spread by several independent media centers, indymedia.
I think the anarchism of the now in Belgium is a lot like that of Sweden, but with less syndicalist influences and a lot more people interested in squatting, because the laws around it are not that strict. It's also close to the anarchism of the Netherlands.
Recently, two people started a new project. Their website, www.anarchyisorder.org, is almost fully in English. The portal site of anarchist groups in Belgium is anarchie.be