Denaturalization is back. In 1967, the Supreme Court declared that denaturalization for any reason other than fraud or mistake in the naturalization process is unconstitutional, forcing the government to abandon its aggressive denaturalization campaigns. For the last half century, the government denaturalized no more than a handful of people every year. Over the past year, however, the Trump Administration has revived denaturalization. The Administration has targeted 700,000 naturalized American citizens for investigation and has hired dozens of lawyers and staff members to work in a newly created office devoted to investigating and prosecuting denaturalization cases. Using information gathered from responses to Freedom of Information Act requests, legal filings, and interviews, this Essay is the first to describe the Trump Administration’s denaturalization campaign in detail. The Essay then situates denaturalization within the Trump Administration’s broader approach to immigration. Under a policy known as “attrition through enforcement,” the Trump Administration has sought to discourage immigration and encourage “self-deportation.” Although attrition through enforcement is typically described as a method of persuading unauthorized immigrants to leave the United States, the denaturalization campaign and other Trump Administration initiatives suggest that the same approach is now being applied to those with legal status.