Lexington was first settled circa 1642[3] as part of Cambridge, Massachusetts. What is now Lexington was then incorporated as a parish, called Cambridge Farms, in 1691. This allowed them to have a separate church and minister, but were still under jurisdiction of the Town of Cambridge. Lexington was incorporated as a separate town in 1713. It was then that it got the name Lexington. How it received its name is the subject of some controversy. Some people believe that it was named in honor of Lord Lexington, an English peer.[5] Some, on the other hand, believe that it was named after Lexington (which was pronounced and is today spelled Laxton) in Nottinghamshire, England.

In the early colonial days, Vine Brook, which runs through Lexington, Burlington, and Bedford, and then empties into the Shawsheen River, was a focal point of the farming and industry of the town. It provided for many types of mills, and in the 20th Century, for farm irrigation. For decades, Lexington grew modestly while remaining largely a farming community, providing Boston with much of its produce.