These agencies were chosen for the case studies because they involve six cities that have experienced some of the most contentious local battles on this issue in recent memory. The case studies were conducted between December 2006 and September 2009. The jurisdictions studied are New Haven, CT; Prince William County, VA; Montgomery County, MD; Phoenix, AZ; Mesa, AZ; and Minneapolis, MN. New Haven confronted the issue of undocumented immigrants who lacked legitimate proof of identification. Two of the case studies - Prince William County, VA, and Montgomery County, MD - feature the role played by police chiefs in two suburban areas of Washington, DC, as they were drawn into contentious debates over local enforcement of Federal immigration laws. In another case study, the Phoenix Police Department faces the same issues as other cities, but at a higher level of urgency and with an added complication, i.e., the police share jurisdiction within city borders with the Maricopa County sheriff, whose hard-line approach to law enforcement is at odds with that of the Phoenix mayor and the police chief. In Mesa, the local police department also shares jurisdiction with the Maricopa County Sheriff's Office. Mesa has used a practical and measured approach that focuses on reducing crime and improving the quality of life for all residents. The Minneapolis Police Department faces a number of issues related to cultural differences posed by a large population of Somali immigrants. The report concludes with a summary of the discussion at the National Summit convened in July 2009 in Phoenix; it includes recommendations for local police agencies and the U.S. Congress regarding immigration issues.