The 1977 preliminary report of Congress entitled 'Prison Population and Policy Choices' focuses on (1) the size of the correctional population under custody, (2) the capacity of correctional facilities to hold the correctional population in custody, and (3) the conditions that characterize the custody of the correctional population. Although the data are still undergoing final analysis, preliminary results show clear broad trends. On the day of the survey, only about 7 percent of all cells were vacant, and there were six inmates for every five units of physical capacity. The smallest standard of area which any standard-making body has adopted is 60 square feet per inmate. Only 45 percent of State prison cells and 40 percent of local jail cells meet or exceed this standard. Standards as high as 80 square feet have been proposed. Only 10 percent of State cells and 20 percent of local jail cells meet or exceed this more rigorous standard. Smaller confinement units characterize older institutions and are more likely in the South and West than in the Northeast and Northcentral States. About two out of every three inmates share a confinement unit with at least one other inmate. These occupancy and density data do not necessarily indicate crowding, when crowding is defined as lack of space, along with other physical, social, and personal factors, which results in inmate stress. The discussion of crowding in prisons and jails should consider other variables in addition to density and occupancy. Graphic and tabular data from the study are provided.