They join the already announced Kate Burton and Fiona Gallagher, whose involvement was first reported by Playbill On-Line.
Will Frears, who piloted Rebeck's Omnium Gatherum, directs.
The work, about a man who returns to his family after a 17-year absence, explores "the mysteries of time and memory" and "the question, 'What wouldn't you do for your child?'"
Gallagher is known to Williamstown audiences. She was part of the 2001 season, acting in Elmer Rice's Street Scene. In New York, she is perhaps best known for her title performance in Gretty Good Time at the Ensemble Studio Theatre. She is currently Off-Broadway in Trust.
Cleevely was seen at WTF in La Ronde in 1997. Gaston, who acted in A Day in the Death of Joe Egg on Broadway, performed in Landscape of the Body during Williamstown's 2003 season. Austin Lysy has spent two previous summers with the festival. Sets will be designed by Thomas Lynch, costumes by Junghyun Georgia Lee, lights by Frances Aronson and sound by David Wallingford.
The 2004 festival schedule runs as follows:
The Water's Edge, June 23-July 4
Rodney's Wife, July 7-18
R Shomon, July 21-Aug. 1
Dedication or The Stuff of Dreams , Aug. 11-22
The Festival Box Office at the Adams Memorial Theatre will open on June 15 at 11 AM. Tickets may be purchased beginning June 15 by calling (413) 597-3400, or by visiting the box office in person. Mail orders received prior to June 15 will be processed before the Box Office officially opens to the public.
For the latest updates on casting and events, or to receive a season brochure by mail, patrons are encouraged to visit WTF's official website at www.WTFestival.org.