The tradition dates to 1912, when a group of seniors, fed up with the dry cleaning bills after visits to the bar at the Nassau Inn, adopted easily washable blue denim overalls and jackets for their drinking sessions. Members of the Class of 1913 followed this lead, dubbing their attire "beer suits." The Class of 1914 substituted white duck for the blue denim. The tradition lapsed during World War I, but was revived in 1919.
The beer suit became the beer jacket around the middle of the 20th century, when the overalls were discarded. In recent years it was renamed the senior jacket to signify its role in identifying and uniting the members of the graduating class. Each class jacket carries a distinctive logo, usually chosen through a design contest, which becomes an unofficial emblem of the class.
Reunion jackets are issued to alumni returning to their 25th reunions, in honor of what is traditionally the most important and best-attended reunion.
Most major reunions up to the 25th have costumes that reflect the class reunion theme. These costumes may be simple or elaborate depending on the resources available and the ambition of the reunion committee.