Beginning in May 1974, Oberlin adopted a "Cluster Plan" for Commencement/Reunion Weekend.
The Cluster Plan enabled reunion-year alumni to return to campus with friends who graduated a year or two before or after them.
The sample chart shows, for example, the classes of 1955, 1970, 1985, and 2005, which observed their respective 60th, 45th, 30th and 10th reunions in May 2015. They could return in May 2016 for cluster reunions with the classes of 1956, 1957, 1971, 1972, 1986, 1987, 2006, and 2007. The classes of 1996 and 1991 would observe traditional 50th and 25th class reunions.
All alumni are welcome back at any Commencement/Reunion Weekend whether celebrating a specific reunion or not.