The past decades have been characterized by sharp increases in the number of families, mainly from Central America's Northern Triangle, apprehended by US Border Patrol. In an effort to stem those flows, the Trump administration implemented a zero-tolerance policy (ZTP) aimed at criminally prosecuting all adults crossing the border without authorization, regardless of whether they traveled with children or sought asylum upon entry. Thousands of children were separated from their parents, reclassified as “unaccompanied,” and referred to the custody of the Office of Refugee Resettlement (ORR). Yet, to date, there has not been a careful evaluation of the impacts of the policy. We examine how ZTP affected the volume of unaccompanied minors, their time in ORR custody, and their likelihood of family reunification. We show that ZTP boosted the ranks of unaccompanied children through family separations by 48 percent, lowered their discharge rate from ORR's custody by 38 percent, and reduced their odds of family reunification by 49 percent. Given the growing number of families from the Northern Triangle seeking asylum in the United States, the documented mental health problems of separated children, and the rotating nature of immigration policies based on the administration in place, understanding the implications of policies like ZTP is imperative.