AMAS Musical Theatre was founded by Rosetta LeNoire, whose career as an actress began in 1939 and has spanned the Broadway stage, film and television. Miss LeNoire conceived of the idea for the company in 1968-1969 in response to the rift she observed between African Americans and whites during that period. AMAS means “you love” in Latin and the multiracial theater, one of the first in New York City, “where all people could work together, with respect for individual skills and talents, rather than for race or color” is Miss LeNoire's method of positively affecting change in the community.

AMAS was incorporated in April 1969 as a non-profit performing arts company. Actors for the first production, “Soul, Yesterday and Today,” based on Langston Hughes' poetry, began rehearsals in the basement of Miss LeNoire's Bronx home. Originally known as AMAS Repertory Theatre, its name was changed in 1989 to reflect its focus on musical theater. During the 1970's AMAS moved to different locations, usually in churches on the Upper West Side of Manhattan, in 1977 to Fifth Avenue and 104 Street, and in 1992 to the theater district on West 42 Street. premiered at AMAS and was later produced as a commercial film with actor Jon Voight. Serving as AMAS's artistic director, Miss LeNoire has overseen the creation of over forty original musicals including (which went on to a two-year run on Broadway and a Tony Award nomination for best musical), It's So Nice to Be Civilized, Bojangles (also performed on Broadway), Jam, Juba, Blackberries, and The Mainstage Musical Theatre, as the production company is known, provides opportunities for writers, composers and lyricists to create new works, free of the pressures of the commercial stage. Some of the actors belong to the Actors Equity Association, others are independent. AMAS employs experienced, often renowned directors and choreographers to work with fledging creators. In the 1980's AMAS staged 4-5 productions each season, as of the late 1990's due to financial considerations, it averages two or three per season.

In the 1970's-1980's AMAS sponsored the Eubie Blake Youth Theatre where training in music theory, drama, vocal technique, dance-movement and stagecraft was offered to youths aged 10 through 18. In addition to the classes, students participated in the yearly productions of the Eubie Blake Youth Theatre. Other programs AMAS sponsored include the Adult Workshop, which offered free training to low income artists, and the Summer Tour which brought free original musicals to senior citizen centers and nursing homes. Performers were recruited and trained through these two programs. Audiences have been built through in-school programs and by bringing children and other community members into AMAS with free performances and free ticket programs.

In the late 1990's, while the focus of AMAS has remained similar, the programs have been modified slightly. The Eubie Blake Youth Theatre has been re-named the Rosetta LeNoire Musical Theatre Academy and is a pre-professional musical theater training program for inner-city teenagers. The program culminates with a full Off-off Broadway production. Another school oriented program is the Rosetta LeNoire Immigration Experience, an artists-in-residence school project for New York City elementary school children. The students interview immigrants and make a presentation along with a book based on their research. In addition to the Mainstage Productions (which remains the heart of AMAS), this theater company also offers the Six O'Clock Musical Theatre Lab, a development series for writers, lyricists and composers where new shows and works-in-progress are presented. Free performances and free ticket programs continue to be a primary means of building audiences.

AMAS has won many prestigious awards. Significantly, the Actor's Equity Association established the Rosetta LeNoire Annual Award in 1989 and chose her to be the first recipient in recognition of her outstanding “artistic contributions to the universality of the human experience in the American Theatre.” Additionally, AMAS has received the Mayor's Award of Honor for Art and Culture; the Manhattan's Borough's President Award-Excellence in Theatre, and the Audicne Development Corporation (AUDELCO) Awards in 1979, 1982, 1984, and 1986, among others.