The mean number of disciplinary reports for five infraction categories was compared for both groups. The group of mentally retarded inmates included 170 cases considered to be representative based on sex, age, and commitment offense. The matched group of nonretarded inmates also included 170 cases. A comparison of disciplinary reports revealed two major findings. Youthful mentally retarded and nonretarded inmates did not adjust to incarceration in a similar manner, and behavior in prison was significantly different across infraction categories for mentally retarded and nonretarded inmates. It is speculated that adaptive behavior deficits of mentally retarded individuals will result in poor overall adjustment by incarcerated youth. 16 references, 1 table. (Author abstract modified)