The purpose of this article is to inform the debate about strategies and options for countering online radicalization within the U.S. domestic context. Its aim is to provide a better understanding of how the Internet facilitates radicalization; an appreciation of the dilemmas and tradeoffs that are involved in countering online radicalization within the United States; and ideas and best practices for making the emerging approach and strategy richer and more effective. It argues that online radicalization can be dealt with in three ways. Approaches aimed at restricting freedom of speech and removing content from the Internet are not only the least desirable, they are also the least effective. Instead, government should play a more energetic role in reducing the demand for radicalization and violent extremist messages—for example,by encouraging civic challenges to extremist narratives and by promoting awareness and education of young people. In the short term,the most promising way for dealing with the presence of violent extremists and their propaganda on the Internet is to exploit their online communications to gain intelligence and gather evidence in the most comprehensive and systematic fashion possible.