Marvelwood was founded in 1956 by Robert A. Bodkin and Ian Hanna in Cornwall, Connecticut, on a campus previously occupied by Rumsey Hall School.

Ian Hanna named the school after his relative, Donald Grant Mitchell, an American novelist who owned an estate in New Haven, Connecticut, also called Marvelwood.

Blythe Everett, parents of 2014–16, is the current head of the school.

The school offers a three-level ESL program for foreign speakers.

Marvelwood works locally with the Audubon Sharon and Institute for Bird Populations.