Theater at Monmouth is a year-round repertory company of professional theatre artists from across Maine and the United States. Founded in 1970, the Theater was named The Shakespearean Theater of Maine by the Maine State Legislature in 1975. Performances are held in Cumston Hall, listed on the National Register of Historic Buildings since 1976.

The mission of Theater at Monmouth is to present innovative approaches to Shakespeare and other classic plays through professional productions that enrich the lives of people throughout the state of Maine. In its 50 seasons, TAM has presented more than 350 productions in its three-month Summer Repertory Season, including 28 world premieres, entertaining audiences from 36 states and through Education Tours in the fall and spring annually reaching more than 15,000 students.

Theater at Monmouth education programs strive to deepen understanding of, appreciation for, and connection to great literature. Education programs aim to build analytical and literacy skills; to inspire imaginative thinking and foster creativity; and to increase confidence, self-esteem, and a sense of community. TAM works in partnership with community-based arts, cultural, and service organizations using theatre to build community and enhance civic engagement.

Theater at Monmouth is a constituent member of Theater Communications Group, the Shakespeare Theater Association, the Winthrop Chamber of Commerce, the Kennebec Valley Chamber of Commerce, and the Androscoggin Chamber of Commerce.

From its inception, Theater at Monmouth has maintained strong community partnerships, education programs, and humanities initiatives. Through collaborations with such institutions as the University of Maine at Augusta, the Maine Humanities Council, Arts Midwest, the National Endowment for the Arts, the Maine Arts Commission, The Holocaust and Human Rights Center of Maine, Cumston Hall Public Library, and schools across the state, the Theater provides educational, scholarly, and artistic experiences for Maine residents of all ages.