What is today the Midcoast Symphony Orchestra began in 1990 as the Midcoast Chamber Orchestra, a small ensemble formed to play orchestral music. During the next decade, the group expanded so that it could perform a wider range of the orchestral literature. Today it is an ensemble of 60 musicians, includes all the instruments of the modern symphony orchestra, and performs a wide range of music from the classical to the modern periods.

Although it has grown from the original chamber group, the Midcoast remains a community orchestra, formed of volunteer musicians who come to Topsham each week during the concert season from an area along the coast south of Portland and north to Newcastle, and inland from Augusta, Gardiner, and the Lewiston-Auburn area. Some are music teachers by day, others represent a wide range of professions, and some are retired. They are drawn together by a love of music and their desire to play the great works for symphony orchestra.

The Orchestra's home is the Orion Performing Arts Center at the Mt. Ararat Middle School in Topsham. In addition to its concert series at the Orion, orchestra repeats each of its concerts at the Franco-American Heritage Center in Lewiston.