A cotillion or debutante ball is a formal presentation of young ladies, debutantes, to polite society.

Debutants are usually recommended by a distinguished committee or sponsored by an established member of society.

Modern cotillions are often charity events; the parents of the debutante donate a certain amount of money to the designated cause, and the invited guests pay for their tickets. Cottillions may be elaborate formal affairs and involve not only 'debs' but junior debutantes, escorts and ushers, flower girls and pages as well.

Some notable debutante balls:

• Atlanta, Georgia: The Harvest Ball , The Christmas Ball
• Baltimore, Maryland: The Bachelor's Cotillion
• Boston, Massachusetts: The Cotillion
• Charleston, South Carolina: The St. Cecilia Ball
• Chicago, Illinois: The Passavant Cotillion , The Christmas Ball
• Cincinnati, Ohio: The Bachelor's Cotillion
• Cleveland, Ohio: The Assembly Ball , The Cotillion Society Ball
• Kansas City, Missouri: The Jewel Ball
• Memphis, Tennessee: The Holiday Ball , The Summer Presentation Ball
• New Orleans, Louisiana: The Debutante Club Ball , Le Debut des Jeunes Filles de la Nouvelle Orleans
• New York, New York: The Junior Assemblies
• Philadelphia, Pennsylvania: The Assembly
• Raleigh, North Carolina: The North Carolina Debutante Ball
• Richmond, Virginia: The Bal Du Bois
• St. Louis, Missouri: The Veiled Prophet Ball
• San Francisco, California: The Cotillion
• Savannah, Georgia: The Christmas Cotillion
• Washington, D.C.: The National Debutante Cotillion and Thanksgiving Ball , 55 years old in 2004. The beneficiary is Children's National Medical Center.

The Cotillion was a popular 18th and 19th century dance in the French Courts that preceded the Quadrille style of dancing.