Originally known as Cambridge Farms, Lexington was first settled in 1642. Additional residents were soon attracted by the availability of hay fields and farming acreage and the possibilities of land speculation. Early settlers formed their own parish in 1691 to avoid traveling into Cambridge, and soon thereafter, Lexington was incorporated in 1713.

The town remained a quiet farming community until April 1775. With a total population at that time of seven hundred, the town played a pivotal role in United States history when the "Skirmish on the Green" began the American Revolution. It was in Lexington, Massachusetts, on the morning of April 19, 1775, that "the first blood was spilt in the dispute with Great Britain" according to Washington's diary, when colonists faced British regulars. In this first skirmish, eight Minutemen lost their lives, ten were wounded, and two British soldiers were also wounded. After the battle, Samuel Adams exclaimed to John Hancock, "What a glorious morning for America!"

In 1846, the extension of a railroad line from Boston made commuting possible, bringing more travelers into the town. Lexington soon became known as a summer resort providing a healthy and invigorating atmosphere. Following World War II, population and residential building increased dramatically, and academicians and high-tech associates became neighbors of descendants of the early settlers. Colonial structures and Victorian mansions were joined by award winning contemporary architecture. East Lexington in the 19th century had been the scene of debates on such issues as abolition and temperance, and the interests in education which had been the foundation for establishing the first normal school in the United States has continued to flourish. Concerned about maintaining the residential quality of the town while providing services, Lexington citizens established one of the country's first planning boards, and zoning regulations. Today Lexington proudly preserves its history while continuing to support its reputation for progressive action and independent spirit.