Free recall of weakly categorizable words was compared in hyperactive (ADDH), reading-disabled, and normal boys. During a baseline trial, hyperactive boys recalled fewer words and showed less category organization than both reading-disabled and normal boys. Following a manipulation designed to encourage semantic encoding of words, hyperactive boys showed an immediate improvement in item recall and organization so that their free-recall performance was similar to that of reading-disabled and normal children. During later trials of a multiple-trial format, hyperactive boys recalled fewer words than did the reading-disabled and normal boys, despite maintaining equality in category organization. Rather than lacking the skill to use semantic organization as a strategy in free recall, hyperactive boys had difficulty in spontaneously generating the organizational strategy in response to instructions to remember and sustaining sufficient effort to task completion.