As the building was under construction, plans for a third floor were scrapped as it would affect local businessman and banker Elias C. Benedict’s travel to New York City.

He commuted by sailboat and the third floor would disrupt his sight of the flag signals that notified him when the crew was ready to sail.

This was voted down by the Representative Town Meeting (RTM), so the Board of Education instead approved one high school at Put's Hill.

Twenty years later, in 1990, the town added a new science wing, the Black Box Theater and additional classrooms, extended and refurbished the locker rooms, and renovated the auditorium, the swimming pool and the courtyard.

Then, a state-of-the-art Performing Arts Center opened in October 2015, replacing part of the parking lot.

[9] In the school course guide, additional requirements include the following: Students' grade point averages are calculated on a weighted scale.

[10] Greenwich High School students have opportunities to participate in a variety of sports in the Fairfield County Interscholastic Athletic Conference (FCIAC).

Both boys and girls teams compete in the FCIAC in the following sports (although some sports such as football are not played by any girls' teams while softball is not played by any boys' teams): football, soccer, basketball, cheerleading, ice hockey, field hockey, track and field, cross country, swimming, water polo, rugby, golf, bowling, baseball, softball, volleyball, wrestling, gymnastics, and lacrosse.