Information was collected from 272 files for the inmate population in cell restriction as of March 1998 and from log books that documented rule violations. Fifty-two percent of inmates had drug problems, 73 percent had social problems, 48 percent had vocational problems, 20 percent had sexual problems, and 18 percent had serious psychological problems. Inmates on lockup could be categorized into four relatively homogeneous groups: low IQ-violent inmates, older long-term inmates, young short-term inmates, and young lifestyle criminals. Two special types of problem inmates were identified, violent offenders and chronic offenders. In the past year, the rule for disobeying a lawful order was broken 294 times by the 272 inmates. Obstructive or disruptive conduct was reported 283 times, and there were 259 cases of unauthorized possession and 204 cases of verbal abuse. Nearly half the rule violation dispositions resulted in 30 days or less in cell restriction. Sanctions imposed for assault, threats, intimidation, verbal abuse, and obstructive or disruptive conduct were fairly consistent. About 76 percent of the 272 inmates were in cell restriction status; another 6.3 percent were in summary segregation and 0.4 percent were in investigative segregation and security hold. Approximately 41 percent of those in cell restriction were confined for 1-5 years, while 15 percent were restricted for more than 10 years. Appendixes contain a timeline chronology for the Iowa State Penitentiary, the lifestyle criminality screening form used in the study, and the data collection instrument. 21 references, 10 tables, and 16 figures