Accumulating studies are documenting specific motivational variables that, when combined into a naturalistic teaching paradigm, reliably influence the effectiveness of language teaching interactions for children with autism. However, the effectiveness of this approach has not yet been assessed with respect to improving speech intelligibility. The purpose of this study was to systematically compare two intervention conditions, a Naturalistic approach (which incorporated motivational variables) vs. an Analog (more traditional, structured) approach, with developmentally similar speech sounds equated within and across conditions for each child. Data indicate that although both methods effectively increased correct production of the target sounds under some conditions, functional use of the target sounds in conversation occurred only when the naturalistic procedures were used during intervention. Results are discussed in terms of pivotal variables that may produce improvements in speech sounds during conversational speech.