Few Americans would question the importance of the amendment to the Constitution that serves as the blueprint for personal liberty and the subject of this encyclopedia. However imperfectly Americans understand or honor the principles embodied in the core First Amendment freedoms, most would express pride in them — in worshiping or not worshiping according to the dictates of their conscience, expressing their opinions, assembling and associating with whomever they please, and petitioning the government. Hardly anyone would restrict any of these rights as they apply to themselves however much they might be tempted to constrain their application to others whose beliefs or behaviors they find distasteful or even abhorrent.

Americans generally share this heritage with their English forebears, whose roots in turn drew from Reformation theology and Greek and Roman ideals of democratic citizenship. Individuals who believed they were directly accountable to God wanted to be able to pursue spiritual truth wherever it led them, and some colonists, such as Roger Williams, challenged the religious establishments of some denominations brought to the New World. To influence government, citizens needed access to information. To participate in government, citizens needed to be able to express their opinions. The 1735 trial of John Peter Zenger in New York was reported throughout the colonies and indicated that while freedom of speech and press did not necessarily exempt colonial-era publishers from prosecution, the truth of their accusations was a defense, and defendants would be entitled to allow juries of their own peers to decide on such truth.

As American colonists approached independence, freedoms later embodied in the First Amendment assumed increasing importance. After ratification of the Constitution, citizens demanded that these rights be embodied in a bill of rights. Each subsequent period in U.S. history has added context to these guarantees, allowing contemporaries to draw valuable lessons not only from those times when such rights triumphed but also from times when they were jeopardized.