Thomas Paine's Common Sense, published in Philadelphia on January 9, 1776, is the most consequential pamphlet in American history. In the single year between July 1775 and July 1776, American colonists went from professing devotion to King George III to declaring themselves absolved of all allegiance to the British Crown. Common Sense was the chief catalyst for that change. In six months it transformed a continent of bewildered British subjects into a nation of republican Americans. This 250th Anniversary Edition is the only modern reprint derived directly from the Bradford/Towne printing of February 14, 1776 - the edition Paine himself supervised, expanded, and considered definitive. The source copy is held in the Charles Deering Library at Northwestern University. Ben Ponder, Ph.D., whose scholarly edition of this text formed the basis of his book American Independence: From Common Sense to the Declaration, provides a substantial new introduction, "The About-Face of 1776," tracing Paine's unlikely biography, the seven thematic arguments of the pamphlet, its extraordinary reach and reception, and an account of the most compressed and consequential shift in public opinion in the history of democratic government during the spring of 1776. A chronology of key events leading to American independence from 1774 to 1776 is included as back matter.