On 1January 2006, Enghien had a total population of 11,980. The total area is 40.59 km2 (15.67 sq mi), which gives a population density of 295 inhabitants per km2.
The municipality consists of the following districts: Enghien, Marcq, and Petit-Enghien. It is situated on the Flemish border, and restricted language rights are granted to the Dutch speaking minority (so-called language facilities).
In 1566, the county of Enghien was elevated to a duchy-peerage. However, the necessary registration process was not completed, so the title became extinct at the death of Louis I de Bourbon in 1569. In 1633, Henry II, Prince of Condé, grandson of Louis I de Bourbon, inherited the duchy of Montmorency, near Paris, after the execution of Henri II de Montmorency, brother of his wife Charlotte-Marguerite de Montmorency. In 1689, King Louis XIV allowed Henry III, Prince of Condé, grandson of Henry II, Prince of Condé, to rename the duchy of Montmorency as "duchy of Enghien", in memory of the duchy of Enghien which the Princes of Condé had lost in 1569 at the death of Louis I de Bourbon.
The city of Montmorency, at the heart of the duchy, continued to be known as "Montmorency", despite the official name change, but the name "Enghien" stuck to the nearby lake and marshland that developed later as a spa resort and was incorporated as the commune of Enghien-les-Bains in the 19th century.