With a communal reform of 1975 the independent municipalities of Breitscheid, Eggerscheidt, Hösel, Lintorf (seat Angerland) as well as the local part of Homberg and the municipality of Homberg-Meiersberg (seat Hubbelrath) were added into the city of Ratingen.
Ratingen was settled before 849. Since the Middle Ages, the Ratingen area belonged to the count and later dukes of Berg. On December 11, 1276 the settlement received city rights. Ratingen was one of the four places of Berg which experienced an economic boom in the end of the Middle Ages, but slowed down during the Thirty Years' War. At the beginning of the Industrial Age, the first manufacturing plants opened in 1783. In Cromford the first mechanical spinnery of Europe opened, which grew into the Textilfabrik Cromford, now part of the Rheinisches Industriemuseum (Rhine Industry Museum). In the Napoleonic times, it became part of the city of Berg and in 1815, into the Kingdom of Prussia.
In the communal re-organization of 1929, Ratingen maintained its independence. After relatively small war damage, Ratingen in the 1960s and the 1970s experienced years the growth and development (West Ratingen with 20,000 inhabitants, developed in the late 1960s-1980s). Several important international enterprises (particularly from the IT industry) as Vodafone, Sun Microsystems, Hewlett-Packard, SAP, CEMEX, Tiptel and Esprit maintain branches and/or main centers in Ratingen. In 1970, before further incorporations the number of inhabitants surpassed 50,000.