Abstract: If we are committed to freedom of speech, must we tolerate lies? This essay provides a framework for thinking about this and other questions regarding falsehoods. The framework focuses on four sets of issues: (1) the speaker’s state of mind, and the (2) magnitude, (3) likelihood, and (4) timing of harm. From this way of thinking about the problem, we can see that current constitutional law fails to strike the right balance. Public officials and public figures should be able to do far more than they are now permitted to do to respond to defamation, as should ordinary citizens subjected to damaging falsehoods. The government should be able to restrict and punish certain kinds of lies and falsehoods that pose serious threats to public health and safety. To protect the democratic process, the government should be able to regulate other kinds of even nondefamatory falsehoods. The essay draws attention to the sheer diversity of tools available to the government. The government need not censor or punish; it might, for example, require disclosure, labels, or warnings, or some form of choice architecture that reduces the likelihood that falsehoods will spread.