Born in Danville, Vermont, in 1792, he graduated from Dartmouth in 1814, and moved to York, Pennsylvania. He was admitted to the bar and practiced law in Gettysburg, PA for fourteen years.

He became leader of the radical Whigs and Free-soilers in the U.S. Congress, from 1849-53. He took a leading part in organizing the Republican Party in the state of Pennsylvania.

On July 4, 1861, Stevens became chairman of the Ways and Means Committee, where in his outstanding work, inspired a similar great Statesman, James G. Blaine, to write "Thaddeus Stevens was the natural leader who assumed his place by common consent."

In the joint Committee he introduced what became the Fourteenth Amendment to the Constitution, and also the Reconstruction Act, in 1867.