Born to a wealthy Boston family, Adams attended Harvard College where he received a bachelor's degree in 1740 and a Master of Arts degree in 1743; prophetically, the subject of his master's thesis was "Whether it be lawful to resist the supreme magistrate if the commonwealth cannot otherwise be preserved."
After he completed his college education Adams and his father began a partnership in a brewery. Adams's father, however, soon lost most of his wealth due to the failure of an investment venture in paper currency, which was made illegal by the British government in 1744, thus exacerbating the family's dislike for the central government. The elder Adams died in 1748, and Samuel took full charge of the family brewery.
Adams in the meantime became tax collector of Boston and was vocal in town meetings, which brought him significant political influence among his peers. When the brewery, never enormously profitable, failed in 1764, Adams began devoting himself full-time to political matters, first drafting the colony's negative response to the Sugar Act in May 1764, and the next year being elected to a seat in the Massachusetts colonial legislature (called the "general court"), where he immediately became a vocal opponent of the Stamp Act, even to the extent of helping to instigate Boston's Stamp Act riots of that year.
While a member of the legislature Adams served as clerk of the house, in which capacity he was responsible for drafting written protests of various British governmental acts during his tenure, which continued to 1774. Notable among these was a circular letter he drafted as a response to the 1767 Townshend Acts, distributed among the other twelve colonies in a bid to achieve a united front of resistance to these acts. The failure of the legislature to rescind the contents of this letter at the express demand of King George is usually cited as one of the main factors resulting in the stationing of troops in Boston beginning in 1768.
This British troop presence in Boston, aggravated by protest activities such Adams' formation of the Non-Importation Association, led to the Boston Massacre (a term coined by Adams) two years later. After the incident Adams chaired a town meeting which formed a petition, presented to acting governor Thomas Hutchinson, demanding the removal of two British regiments from Boston proper. Hutchinson at first claimed no responsibility for the matter, owing to his temporary status as governor, but stated he would be willing to move one regiment; the meeting was re-convened and Adams successfully urged the crowd of over 5,000 present to stand firm on the terms: "Both regiments or none!" Fearing open warfare, Hutchinson had both regiments removed to Castle William, an old fort on an island in Boston Harbor. These regiments would thereafter be known in the British Parliament as "The Sam Adams Regiments."
In 1772, after a British declaration that judges should be paid by the Crown rather than by the colonial legislatures, a demand from the people of Boston for a special session of the legislature to reconsider this matter was refused by Hutchinson. It was at this point Adams devised a system of Committees of Correspondence, whereby the towns of Massachusetts would consult with each other concerning political matters via messages. Such a scheme was still technically legal under British law, but led to a de facto colonial legislative body. Dabney Carr of Virginia later proposed the adoption of this system throughout the thirteen colonies, which led eventually to the formation of the Continental Congress.
Adams is perhaps best remembered for helping to organize, with William Molineux, the Boston Tea Party of December 16, 1773, in response to the Tea Act. As British tea-ships sat in Boston Harbor awaiting payment of the import duties, Adams energized a large crowd gathered at the port with his oratory, and later donned costume and led a band of men aboard ship where they dumped the tea into the harbor, to the delight of the assembled spectators on shore.
In response to this escapade, Parliament passed what were later to be known as the "Intolerable Acts," which called for the revocation of the colonial charter of Massachusetts and the closing of the port of Boston. Reaction from the colonies was to expedite the opening of a Continental Congress, and when the Massachusetts legislature met in Salem on June 17, 1774, Adams locked the doors and made a motion for the formation of a colonial delegation to attend the Congress. A loyalist member, faking illness, was excused from the assembly and immediately went to the governor, who issued a writ for the legislature's dissolution; however, when the legislator returned to find a locked door, he could do nothing.
Adams was one of the major proponents of the Suffolk Resolves drafted in response to the Intolerable Acts, and adopted in September 1774. Also that month the Continental Congress held its first meeting, and Adams retired from the legislature and was sent to Philadelphia as a representative from the Massachusetts colony. During his time in the Congress he was from the beginning one of the most vocal proponents of independence. (Notably, only he and John Hancock were exempted from the general amnesty offered by Thomas Gage to Massachusetts rebels in 1775.) After signing the Declaration in 1776, Adams, wary of a strong central government, was instrumental in the development and adoption of the loose government embodied in the Articles of Confederation, to which he was also a signatory in 1777. He continued serving in the Congress until 1781, when he was elected to the state senate of Massachusetts. He served in that body until 1788, becoming its president.
At the time of the drafting of the United States Constitution, Adams was considered an anti-federalist, but more moderate than others of that ilk. His contemporaries nicknamed him "the last Puritan" for his views; in 1788 he would write in his diary regarding the federalist and anti-federalist factions, "Neither Interest, I fear, display that Sobriety of Manners, Temperance, or Frugality—among other manly Virtues—which once were the Glory and Strength of our Christian Sparta on the Bay...". He finally came in on the side of ratification, with the stipulation that a bill of rights be added. Additionally, Adams was a member of the conventions that drafted the first Massachusetts state constitution in 1779, and the second one in 1788.
He stood unsuccessfully for election to the House of Representatives for the first Congress, but was elected Lieutenant Governor of Massachusetts, serving from 1789-94. He was elected as governor in 1793 to succeed John Hancock, and served to 1797, afterwards retiring to his home in Boston.
Adams died at the age of 81 and was interred at the Old Granary Burying Ground in Boston. Married twice, he had a son (who died in 1788) and a daughter by his first wife. He was distantly related to John Adams.
Owing to his occupation as a brewer, today a popular brand of Boston beer bears his name.