It is generally agreed that African slaves first arrived in Massachusetts in the 1630's, and slavery was legally sanctioned in 1641. During the colonial era, numerous laws were passed regulating movement and marriage among slaves, and Massachusetts residents actively participated in the slave trade. Historians estimate that between 1755 and 1764, the Massachusetts slave population was approximately 2.2 percent of the total population; the slave population was generally concentrated in the industrial and coastal towns.

As the rhetoric supporting independence of the colonists from Great Britain intensified in the colony of Massachusetts, some noted the glaring inconsistency of arguing for the rights of Englishmen while owning slaves. For example, James Otis, a leading proponent of colonial independence, wrote in a highly regarded and influential 1764 pamphlet that "The colonists are by the law of nature freeborn, as indeed all men are, white or black."

Historian Joanne Pope Melish observed that "the onset of the Revolution both intensified the attack and weakened the structures and practices that supported the institution [of slavery in New England]. . . . New England was not ultimately dependent on slave labor, and the war disrupted patterns of production and trade in the very areas in which slave labor was most heavily engaged; the coastal trade, the provisioning trade with the West Indies, fishing, and shipping in general."

Slaves too were active in seeking the end of slavery in Massachusetts. For example, in 1773, a group of slaves petitioned the General Court (legislature) to end slavery, and directly tied their search for liberty to the colonists' struggles with Great Britain.

As discussed in the section of this website entitled John Adams and the Massachusetts Constitution, the Constitution of 1780 was preceded by a constitution drafted by the legislature and rejected by the voters in 1778. The constitution proposed in 1778 would have recognized slavery as a legal institution, and excluded free African Americans from voting. The Constitution of 1780, in contrast, contained a declaration that "all men are born free and equal, and have . . . the right of enjoying and defending their lives and liberties."