Rosenmontag (Rose Monday) is the highlight of the German "Karneval" (carnival), and is on the Shrove Monday before Ash Wednesday, the beginning of Lent. The "Mardi Gras," though celebrated on Tuesday, is a similar event. Rosenmontag is celebrated in German-speaking countries, including Germany, East Belgium, Austria, and Switzerland, but most heavily in the "Hochburgen" (carnival strongholds), which include the Rhineland, especially in Cologne, Bonn, Düsseldorf, Aachen and Mainz. In contrast to Germany, in Austria, the highlight of the carneval is not Rosenmontag, but Faschingsdienstag (Shrove Tuesday).

The Karneval season begins at 11 minutes past the eleventh hour on the 11th of November and the "street carnival" starts on the Thursday before Rosenmontag, which is known as Weiberfastnacht ("women's carnival"). Karneval is prevalent in Roman Catholic areas and is a continuation of the old Roman traditions of slaves and servants being master for a day. Karneval derives from the Latin carnem levare ("taking leave of meat") marking the beginning of Lent.