Abstract: This study was designed to test four hypotheses related to the Neurolinguistic Programming (NLP) model of Bandler and Grinder and its possible clinical implications relating to language perceptual predicate types to actual levels of performance on language and non-language perceptual tasks. Results provided no supportive evidence for the existence of any relationship between preferred perceptual mode in spoken language predicates and abilities to remember or to perform on tasks capitalizing on different perceptual modes. Nor were there any significant differences found between the inmate sample and the non-inmate comparison sample on preference of kinesthetic mode in language, verbal memory, or performance on the Tactual Performance Test. There was limited support for the notion that individuals can be assigned to primary representational system subgroups on the basis of their natural language predicates. However, it was found necessary to utilize both secondary and tertiary perceptual language modes as well in the classification criteria in order to avoid nearly all of the subjects being classified in the kinesthetic category in both sample groups. The only significant differences in measurements between the two samples were on the scores achieved on the auditory performance task, the Speech Sounds Perception Test, and on the verbal memory story in the visual mode. Both of these measurements showed better performance in the non-inmate sample than in the inmate sample. The study's findings regarding tests of the NLP model indicate that this model holds little relevance for research or clinical application in determining actual levels of internal perceptual processing in any of the perceptual modes. The specific inter-group differences found in the verbal/auditory acuity areas do suggest the need for more detailed study, considering possible implications for the design of inmate treatment programs.