Mark T. Sheehan High School is a public high school located at 142 Hope Hill Road, Wallingford, Connecticut.

Its official colors are burgundy and gold.

[2] Sheehan is known for having started the tradition known as powderpuff.

The first powderpuff game was played in Wallingford between Sheehan and Lyman Hall.

The School is named after Dr. Mark T. Sheehan, a medical officer during World War I, he had also practiced medicine in Wallingford and was known to never deny service to anyone including patients who could not afford care.