Purpose: Syntax has been called the structural foundation of language, as its development allows for more efficient and effective communication. Complex syntax production is known to lag in children and adolescents with language impairment. Conversation, narrative, and expository language sampling contexts are recommended tools for the comprehensive assessment of school-age children, including syntactic abilities. Despite these recommendations, few studies have examined syntactic differences obtained from these three sampling contexts in a within group sample of school-age children, (i.e., ages 8-11 years). Information about similarities and differences in syntactic measures obtained from these three sampling contexts is needed to identify the optimal sampling context(s) for eliciting complex syntax. Method: Conversational, narrative, and expository language samples were elicited from 85 children with typically developing language ages 8;0-11;11 (years; months). Samples were transcribed and analyzed for the mean length of utterance in words and clausal density, or the number of clauses per communication unit as measured by the subordination index. Results: Syntactic measures differed significantly across the three sampling contexts. Namely, narrative and expository language samples elicited longer utterances and more syntactically complex language than conversation samples. Age-related differences in the syntactic measures were not detected. Conclusions: Differences in syntactic measures between conversation and narrative samples and conversation and expository samples within children ages 8-11 years support use of narrative and expository contexts as the most appropriate language sampling contexts for elicitation of complex syntax in school-age children ages 8-11 years. Conversation sampling is unlikely to elicit children's capacities for complex sentence production.