Recent research indicates that a major cause of reading (decoding) disabilities lies in an inability to manipulate speech at its phonemic (phonological) level. The Auditory Discrimination in Depth Program (ADD Program), stimulates basic phonological awareness and has been used extensively at The Reading Foundation in Calgary, Alberta. Here we present pre- and post-test data from 281 clients (ranging from school-age through adulthood) seen over a two-year period; post-test data was collected after 80 hours of ADD instruction. To assess whether significant gains had been achieved, an analysis of covariance was performed, covarying for age and initial vocabulary scores. After 80 hours of intensive instruction, highly significant gains (p<.001) were evident on measures of phonological awareness, sound/symbol connections, word identification, spelling, and decoding in context. In addition to the treatment effect, age and vocabulary had some influence on some of the variables. The data was also analyzed to determine whether the results went beyond a "group effect" only. A total of 229 cases were tabulated for gains or losses on the word attack subtest and on the reading and spelling subtests of the WRAT-R. Results indicate that the remediation was effective for all subjects, though gains on spelling tended to be less than on the two reading scores.