From the Introduction: "Naturalization is the process by which an immigrant attains U.S. citizenship after he or she fulfills requirements established by Congress and outlined in the Immigration and Nationality Act (INA). U.S. immigration policy gives all lawful permanent residents (LPRs) who meet the naturalization requirements the opportunity to become citizens. [...] This report reviews the requirements for naturalization and the rights that come with it. It examines the naturalization process, discusses recent trends regarding who, among the roughly 1 million immigrants entering the United States each year, ultimately becomes a U.S. citizen, and discusses recent naturalization-related policy issues."
CRS Report for Congress, R43366
Congressional Research Service: https://crsreports.congress.gov/