The term "persistent sound system disorder" has been used to describe the speech problems of a relatively small group of children that does not respond readily to treatment. This group includes children who have been given diagnoses such as development apraxia of speech. In this article, a rationale is developed for one approach to the treatment of persistent sound system disorder. This approach, which involves broadening of the phonetic inventory early in the treatment process, is contrasted with more traditional motor-programming treatments that emphasize stabilization of a restricted set of inconsistently produced sounds. The treatment procedures advocated in this article are illustrated in a case study. The article concludes with a discussion of evolving theories and technologies that are likely to impact upon the assessment and treatment of children with persistent sound system disorders in the future.