Purpose: To examine treatment outcomes in relation to the complexity of treatment goals for children with speech sound disorders. Method: The clinical implications of dynamic systems theory in contrast with learnability theory are discussed, especially in the context of target selection decisions for children with speech sound disorders. Detailed phonological analyses of pre-and posttreatment speech samples are provided for 6 children who received treatment in a previously published randomized controlled trial of contrasting approaches to target selection (Rvachew and Nowak, 2001). Three children received treatment for simple target phonemes that did not introduce any new feature contrasts into the children's phonological systems. Three children received treatment for complex targets that represented feature contrasts that were absent from the children's phonological systems. Results: Children who received treatment for simple targets made more progress toward the acquisition of the target sounds and demonstrated emergence of complex untreated segments and feature contrasts. Children who received treatment for complex targets made little measurable gain in phonological development. Conclusions: Treatment outcomes will be enhanced if the clinician selects treatment targets at the segmental and prosodic levels of the phonological system in such a way as to stabilize the child's knowledge of subcomponents that form the foundation for the emergence of more complex phoneme contrasts.