This chapter presents a study that tests the idea, by examining the effects of rehearsal training on digit span and the acoustic-similarity effect in people with severe learning difficulties. Speech rate is seen as an index of the speed with which information can be rehearsed within the articulatory loop. Belmont and Butterfield (1971), were able to improve recall in their subjects with moderate learning difficulties to match the level of age-matched normal control subjects. Memory span for digits and acoustically similar and dissimilar words was assessed before and after rehearsal training in a group of adolescents with severe learning difficulties. If such an improvement could be achieved, it might also have some more general beneficial effects on other cognitive skills known to be related to the operation of short-term memory, such as reasoning, arithmetic, language, and reading skills.