"Welcome to the online public version of the Adjudicator's Field Manual (AFM). The AFM comprehensively details USCIS [U.S. Citizenship and Immigration Services] policies and procedures for adjudicating applications and petitions. USCIS updates the AFM regularly to incorporate new policies and procedures established through statutes, regulations, policy memoranda, or any other pertinent publications."
U.S. Citizenship and Immigration Services: http://www.uscis.gov/