The purpose of this study was to examine the effects of a combined narrative and expository language intervention on third graders' oral language. The participants included 96 third-grade students from two schools in the Mountain West region of the United States. In a quasi-experimental design, all third-grade students in one school (n = 46) were assigned to a treatment condition and all third-grade students in another school in the same school district (n = 50) were assigned to a control condition. Both treatment and control groups received large group oral narrative language intervention led by classroom teachers. The treatment group received additional large group expository language intervention led by the investigators. At posttest, students' narrative retells were analyzed for story grammar and language complexity. Primary and generalized expository outcomes were also analyzed for text structure and language complexity at posttest. Performances of the treatment and control groups were compared using ANCOVA across all measures. The results indicated that the control group and the treatment group did not have statistically significantly different narrative outcomes. However, the treatment group did make statistically significant improvements in expository text structure and some features of expository language complexity across both the primary and generalized expository measures when compared to the control group. This early efficacy study demonstrated the effects of a combined narrative and expository language intervention on expository language of third-grade students over and above narrative language intervention alone. It is possible that a dual focus on narrative and expository oral language instruction will not only impact students' oral language, but also reading comprehension and writing. Future research with a stronger experimental design should investigate the effect of narrative and expository oral language instruction on such distal outcomes.