In order to determine the nature and prevalence of learning deficiencies among adult inmates in U.S. correctional institutions, a sample of subjects was drawn from three institutions in each of the states of Louisiana, Pennsylvania, and Washington. One male maximum security, one male medium security, and one women's prison were selected in each of the three states. Subjects were administered an academic achievement test and an individual intelligence test. Those scoring at or below the fifth-grade level on one of the subtests were deemed to be "learning deficient" and administered a learning disabilities screening test. Subjects with a full-scale IQ of less than 75 were given an adaptive behavior checklist. Data were collected on demographic, family, educational, and criminal justice variables. Findings indicated that the average inmate left school after 10th grade but was performing more than 3 years below this level. At least 42 percent of inmates have some form of learning deficiency, and, of those, 82 percent had indications of specific learning disabilities, especially in the area of auditory and visual discrimination. A substantial number of those identified as learning deficient had been identified previously but little appears to have been done to intervene. It was further found that 70 percent came from unstable home environments and many indicated childhood problems including drug and alcohol abuse and delinquency. Half had no regular employment prior to incarceration. When the relationship between the variables was explored, the most consistent predictor of achievement and measured ability was the highest grade completed. When the analyses were done for the learning deficient versus non-learning deficient sample, ethnic group was the most consistent in explaining the variance. A number of policy recommendations were made as a result of the study. (Author/KC)