Since 2012, there has been a rapid increase in the number of unaccompanied alien children (UAC) apprehended at the U.S.-Mexican border. According to DHS's Customs and Border Protection (CBP), the number of UAC from any country apprehended at the U.S.-Mexican border climbed from more than 24,000 in fiscal year 2012 to nearly 39,000 in fiscal year 2013, and to nearly 69,000 in fiscal year 2014. Prior to fiscal year 2012, the majority of UAC apprehended at the border were Mexican nationals. However, more than half of the UAC apprehended at the border in fiscal year 2013, and 75 percent apprehended in fiscal year 2014 were nationals of El Salvador, Guatemala, and Honduras, according to DHS/CBP. El Salvador, Guatemala, and Honduras face various socioeconomic challenges, which the United States is seeking to address through assistance efforts. This book identifies U.S. mission-level efforts to identify causes of the rapid increase in migration of unaccompanied children and address the causes identified. Furthermore, this book discusses the demographics of unaccompanied alien children while they are in removal proceedings.