[Excerpt] Federal law bars aliens residing without authorization in the United States from most federal benefits; however, there is a widely held perception that many unauthorized aliens obtain such benefits. The degree to which unauthorized resident aliens should be accorded certain rights and privileges as a result of their residence in the United States, along with the duties owed by such aliens given their presence, remains the subject of intense debate in Congress. This report focuses on the policy and legislative debate surrounding unauthorized aliens’ access to federal benefits. Except for a narrow set of specified emergency services and programs, unauthorized aliens are not eligible for federal public benefits. The law (§401(c) of P.L. 104-193) defines federal public benefit as "any grant, contract, loan, professional license, or commercial license provided by an agency of the United States or by appropriated funds of the United States; and any retirement, welfare, health, disability, public or assisted housing, postsecondary education, food assistance, unemployment benefit, or any other similar benefit for which payments or assistance are provided to an individual, household, or family eligibility unit by an agency of the United States or by appropriated funds of the United States". The actual number of unauthorized aliens in the United States is unknown. According to demographer Jeffrey Passel’s calculations based on the 2005 March Current Population Survey (CPS), there were approximately 11.1 million unauthorized aliens residing in the United States (the most recent analysis with detailed statistical breakdowns). Passel further estimated the number of persons living in families in which the head of the household or the spouse was an unauthorized alien was 14.6 million. There were 6.6 million unauthorized families, which he defines as a family unit or solo individual in which the head or spouse is unauthorized. A noteworthy portion of the households headed by unauthorized aliens are likely to have U.S. citizen children, as well as spouses who may be legal permanent residents (LPRs). These “mixed status” families represent about one-third of all unauthorized families and five out of six unauthorized families with children as of March 2005. Policy researcher Steven Camarota concludes (based on his estimates drawn from the 2002 CPS) that the U.S. citizen children of unauthorized aliens account for much of the costs associated with illegal migration. Although the law appears straightforward, the policy on unauthorized aliens’ access to federal benefits is peppered with ongoing controversies and debates. Some center on demographic issues (e.g., how to treat mixed-immigration status families). Others explore unintended consequences, most notably when tightening up the identification requirements results in denying benefits to U.S. citizens. Still others are debates about how broadly the clause “federal public benefit” should be implemented. This report will be updated if policy changes warrant.