Samuel Adams moved from unsuccessful business ventures and municipal work into leadership of Boston's opposition to British imperial policy. As a tax collector and participant in town politics, he built connections among artisans, merchants, and other residents. The Stamp Act crisis of 1765 helped bring him to wider prominence.

Adams worked with James Otis, John Hancock, and other opponents of parliamentary taxation. He helped draft the Massachusetts Circular Letter of 1768, encouraging cooperation among colonial assemblies against the Townshend duties. British troops arrived in Boston that year as resistance intensified. After the Boston Massacre in March 1770, Adams pressed for their removal from the town.

In 1772 he helped establish Boston's committee of correspondence, giving political grievances a durable means of circulation throughout Massachusetts. The controversy over the Tea Act culminated in the destruction of East India Company tea in December 1773. Adams played a leading role in the meetings opposing the tea's landing, although the precise extent of his involvement in planning its destruction cannot be established. Parliament's punitive response drew the colonies toward coordinated action. Adams attended the First Continental Congress in 1774 and supported the Continental Association's boycott.

Adams and Hancock left Boston as confrontation approached, and British attempts to seize military supplies helped precipitate fighting at Lexington and Concord in April 1775. In the Continental Congress Adams favored independence and signed the Declaration in 1776. He also participated in developing the Articles of Confederation. Returning more fully to Massachusetts politics, he contributed to the constitutional convention of 1779–1780 and served in the state senate. During ratification of the federal Constitution he initially expressed reservations but supported acceptance with proposed protections for rights.

He served as lieutenant governor from 1789 and governor from 1794 to 1797, after acting as governor following Hancock's death. His later positions emphasized republican citizenship, education, and vigilance against concentrated power. Adams retired as age and illness limited his activity and died in 1803. His career shows how sustained political communication and local organization helped transform a dispute over imperial administration into a movement for independence and then the practical work of governing a new republic.