In examining the factors that shape the ability of the U.S. Census Bureau to accurately count those confined to correctional facilities, a qualitative case study was conducted to assess the 2010 enumeration in these Group Quarters. These data are also the basis for recommendations about future Census Coverage Measurement to both assess census coverage accuracy and improve census processes in correctional group quarters. The study also identifies social, cultural, operational and other dynamic factors that affect census coverage and may produce coverage errors. The 2010 Census is described through qualitative observations and unstructured interviews in three primary study sites and three secondary sites. The primary sites include two women’s state prisons and one county jail, conducted between March and May 2010. Secondary sites were a large male prison visited during the observation of the American Community Survey (ACS), the state correctional agency main office and a small women’s prison in another state. Problems and successes specifically related to coverage accuracy are also described.