Four treatment case studies of children with speech sound disorders are reported in this chapter to illustrate the implementation of a phonological contrast approach to therapy and to explore the response of different children to this type of intervention. The first case, James, describes in detail pre-therapy assessment, intervention and outcome measurement to illustrate how phonological contrast therapy can be implemented. James' case raises an important issue concerning the interaction between child-specific characteristics and the content, amount and scheduling of therapy. Three additional cases from previously-published group and individual treatment studies (Dodd et al., 2008; McIntosh & Dodd, 2009) are then briefly presented. Service delivery and therapy for these three cases used a phonological contrast approach involving twelve 30-minute sessions scheduled weekly. The children's phonological profiles and history of therapy differed. Comparison of case data allows identification of salient indicators for choice and likely outcome of therapy.