As the capital of Arpajonnais and a historic land of market gardening, the commune has long been a place of trade and known for its fair since the 13th century.
It has now lost the agricultural role (only three farms remain) and commerce favours other communes in the Canton.
It remains, however, with a town centre with plenty of shops gathered around a merchants association.
More than six hundred businesses are located in the commune with nearly a third of these shops.
In 2004 52 new businesses were created in the commune.
Two industrial areas include most of the other businesses: the Belles-Vues and the Butte-aux-Grès, both located in the north of the commune along Route nationale 20.

Arpajon is integrated into the labour pool of Dourdan by INSEE.
In 1999 the Arpajon workforce was 4,433 people divided into 37.4% of employees, 26.4% of middle management, and 15.8% of workers.
Four people were still farmers.
On the same date 9.8% of the population was unemployed and only 20% worked in the commune.
In 2004 the unemployment figure remained almost unchanged at 9.5% of the active population.
With 800 employees, the hospital is the largest employer, followed distantly by the family allowance office (300 staff), the René-Cassin School, and the municipality itself with 200 employees each.

A market is held in the covered market every Friday morning.
As the capital of Arpajonnais and a historic land of market gardening, the commune has long been a place of trade and known for its fair since the 13th century. It has now lost the agricultural role (only three farms remain) and commerce favours other communes in the Canton. It remains, however, with a town centre with plenty of shops gathered around a merchants association. More than six hundred businesses are located in the commune with nearly a third of these shops. In 2004 52 new businesses were created in the commune. Two industrial areas include most of the other businesses: the Belles-Vues and the Butte-aux-Grès, both located in the north of the commune along Route nationale 20.
Arpajon is integrated into the labour pool of Dourdan by INSEE. In 1999 the Arpajon workforce was 4,433 people divided into 37.4% of employees, 26.4% of middle management, and 15.8% of workers. Four people were still farmers. On the same date 9.8% of the population was unemployed and only 20% worked in the commune. In 2004 the unemployment figure remained almost unchanged at 9.5% of the active population. With 800 employees, the hospital is the largest employer, followed distantly by the family allowance office (300 staff), the René-Cassin School, and the municipality itself with 200 employees each.
A market is held in the covered market every Friday morning.
Arpajon