Porter Square is a neighborhood of Cambridge, Massachusetts, located around the intersection of Massachusetts Avenue and Somerville Avenue, between Harvard and Davis Squares. The Porter Square station is one of the stops on the Red Line, and of the Commuter Rail, both part of the MBTA.

Porter Square's most visible landmark is a 46-foot stainless steel kinetic sculpture by Susumu Shingu, entitled "Gift of the Wind."

Porter Square is approximately 200 yards from the border with Somerville, so "Porter Square" inhabitants include residents of both cities.

Porter Square was named for the now-vanished Porter House Hotel . Its specialty was a cut of steak now known as a porterhouse steak.