The purpose of this investigation was to determine the intratester reliability of measurements obtained with the Nicholas Manual Muscle Tester (NMMT) by a tester having minimal experience on individuals with intellectual disabilities. Seventeen individuals classified as moderately mentally retarded between the ages of 14 and 24 (mean = 18.65) were evaluated with the NMMT using a test-retest reliability procedure after a familiarization session. Test-retest strength score relationships for dominant and nondominant elbow flexors and extensors revealed intraclass correlation coefficients from .83 to .86 (p < .001); whereas a series of paired t-tests revealed no significant differences between test and retest values. Finally, intraclass correlation coefficients ranging from .98 to .99 were evident in comparing the first trial to mean of three trials from the first testing session. It was concluded that testers with minimal experience with the NMMT could obtain reliable measurements with the NMMT for determining isometric force of elbow flexors and extensors in individuals with intellectual disabilities.