Barrington was incorporated in 1722 and named for Samuel Shute of Barrington Hall, colonial governor of Massachusetts and New Hampshire. His brother was John Shute Barrington, 1st Viscount Barrington.
The town was made up of two grants, the first containing all of Strafford and present-day Barrington except for a parcel two miles wide called New Portsmouth, or the Two Mile Streak. This second grant had been set aside to provide fuel and home sites for imported workers at the Lamprey River Iron Works, chartered in 1719 by the Massachusetts General Court to encourage industrial development in the province.
Slow at first to be settled because of rocky soil, Barrington by 1810 had 3,564 residents, then the state's third largest town, its primary industry the smelting of iron ore. The Isinglass River, together with its tributaries, provided water power for grist, fulling and saw mills. In 1820, Strafford was set off from Barrington, reducing its land area by about half, because of lengthy travel required to attend town meetings.
In 1882, the Reverend Alonzo Hall Quint writes:
Indeed, the town's attractive natural features, including rivers, brooks, waterfalls and not less than 14 ponds, are summarized by the name of a 374 foot (114 meter) summit: Beauty Hill. Barrington is bisected by the Calef Highway (Route 125), named for a state senator from the 1800s whose family also founded the locally famous general store founded in 1869.