The Boston Tea Party (Dec. 16, 1773) was led by Samuel Adams and other members of the Sons of Liberty, who thinly disguised themselves as Mohawk Indians and boarded ships of British East India Company, dumping 342 chests of tea into Boston Harbor.
Bostonians and other colonists had been subjected to a tax on tea as well as paint, paper, and glass with the passage of the Townshend Acts in 1767. Protests and non-importation movements by the colonists led the repeal of the Townshend duties in 1770, with the exception of the duty on tea. In 1773, Parliament passed the Tea Act which allowed the struggling East India Tea Company to sell a half million pounds of tea in the colonies while bypassing the importation taxes normally paid under the British Navigation Acts. For all practical purposes, the 1773 Tea Act gave the East India Tea Company a monopoly by allowing them to charge less than other merchants. Depsite the fact they were now paying less for tea, American colonists protested the act. Incidents like the Boston Tea Party were avoided in other port cities, when East India ships left without unloading their cargo in the face of protests by colonists. Massachusetts governor Thomas Hutchinson, however, issued an order forbidding ships to leave port without unloading their cargo and this was a key factor that led to the Boston Tea Party.
Tea was especially important in the colonies, because much of the water in America at this time was unsafe to drink, and thus tea was a staple alternative.
References:
John Ferling, A Leap in the Dark: The Struggle to Create the American Republic (Oxford University Press, 2003)
Robert Middlekauff, The Glorious Cause--1048247 09:59, 26 April 2007 (EDT) (rev.ed.) (Oxford University Press, 2005).
Larry Schweikart and Michael Allen, "A Patriot's History of the United States" (Sentinel 2007)