Purpose: The authors created a database of expository oral language samples with the aims of describing the nature of students' expository discourse and providing benchmark data for typically developing preteen and teenage students. Method: Using a favorite game or sport protocol, language samples were collected from 235 typically developing students in Grades 5, 6, 7, and 9. Twelve language measures were summarized from this database and analyses were completed to test for differences across ages and topics. To determine whether distinct dimensions of oral language could be captured with language measures from these expository samples, a factor analysis was completed. Results: Modest differences were observed in language measures across ages and topics. The language measures were effectively classified into four distinct dimensions: syntactic complexity, expository content, discourse difficulties, and lexical diversity. Conclusion: Analysis of expository data provides a functional and curriculum-based assessment that has the potential to allow clinicians to document multiple dimensions of children's expressive language skills. Further development and testing of the database will establish the feasibility of using it to compare individual students' expository discourse skills to those of their typically developing peers.