In 1953, Congress enacted Public Law 280, transferring federal criminal jurisdiction in Indian country to the state government in six states, allowing other states to join in at a later date. This study was designed to gain a better understanding of law enforcement under Public Law 280. Specifically, amid federal concerns about rising crime rates in Indian country and rising victimization rates among Indians, the National Institute of Justice funded this study to advance understanding of this law and its impact, from the point of view of tribal members as well as state and local officials. The research team gathered data from 17 confidential reservation sites, which were selected to ensure a range of features such as region and whether the communities were in Public Law 280 jurisdictions under mandatory, optional, excluded, straggler, or retroceded status. Confidential interviews were conducted with a total of 354 reservation residents, law enforcement officials, and criminal justice personnel. To assess the quality or effectiveness of law enforcement and criminal justice systems under Public Law 280, the research team collected quantitative data pertaining to the responsiveness, availability, quality, and sensitivity of law enforcement, and personal knowledge of Public Law 280.