Long-term unemployment is a category for political action and not a theoretical notion. Nevertheless, taking into account the actual length of unemployment has led to important theoretical adjustments in our reflection on the job market. Analysing long-term unemployment as a complex social and economic universe means that the reference basis of automatic adjustment between job supply and demand based on a price on a price balance, or salary, is questioned, and results in the importance being granted to the actors and regulations which give the structure to these already-constructed systems: strategies for the umemployed to remain on the job market and to fight against losing their qualifications; institutional interventions by public services in employment, via benefit management or the structuring of the job market; the role of intermediaries in activating the systems of qualification and employment procedures working with job supply and demand. These social and institutional dimensional thus appear to be the main organisers of the job market.