Purpose: Production of complex syntax is a hallmark of later language development; however, most of the research examining age-related changes has focused on adolescents or analyzed narrative language samples. Research documenting age-related changes in the production of complex syntax in elementary school-aged children in conversational language samples is limited. Therefore, the purpose of this article is to examine age-related changes in the production of coordinate and subordinate clauses in children between 5 and 10 years of age obtained from 50-utterance conversational language samples. Method: The analytic sample included 196 children with typical language development, who ranged in age from 5;0 to 10;11 (years;months; girls = 103; boys = 96; three cases were excluded). Fifty-utterance conversational language samples were examined for use of coordinate and subordinate clauses. Results: Results of regression analyses indicated that the production of coordinate and subordinate clauses could be predicted from age. The proportion of utterances that included subordinate clauses increased 0.20% for every month increase in age (p < 0.001). Coordinate clauses also continued to grow, although at a slower rate (0.10% increase for every month increase in age, p < 0.001). Finally, the proportion of simple utterances (i.e., utterances without coordinate or subordinate clauses) decreased with age (0.40% decrease for every month increase in age, p < 0.001). Conclusions: This study indicated that as children's age increased, they used fewer, simple, one-clause sentences and more utterances that included subordinate clauses, with or without coordinate clauses. These results were obtained from 50-utterance language samples, further supporting use of language sampling to develop intervention goals and monitor progress in therapy.