Data were drawn from the 1978 National Jail Census and the Jail Overcrowding and Pretrial Detainee Project of the Law Enforcement Assistance Administration. The most significant findings involved the wide variation among jurisdictions in length of stay and the differential use of bed days by different segments of the jail population. Average length of stay ranged from 3 to 35 days, with the average being 9 days. As an example of disparities, the report notes that unsentenced felons stayed an average of 9.4 days in one jurisdiction and 36.6 days in another. The analysis also revealed that few bed days are used by admissions staying only 1 or 2 weeks, even though this group represents a large proportion of jail admissions. These results suggest that jails are being used for different purposes and that jail administrators and policymakers may have more control over jail costs and overcrowding than is commonly believed. Recommendations for further study are included. Tables. (Author abstract modified)