The internal reliability of the WISC-R was examined with a sample of 200 male delinquents. Scale IQ reliabilities ranged from .92 to .80, and subtest reliabilities ranged from .90 to .52. The standard errors of measurement for Scale IQs were approximately 1 point and for individual subtests significantly differed from that reported in the WISC-R manual. The results indicated the WISC-R to be acceptably internally consistent when used with male juvenile delinquents.