Preschool teachers' language use has been described in recent research, as preschoolers' language development is found to be an important preparation for later reading development. Based on existing research on teachers' language use in sociodramatic play, however, it is still unclear how teachers use their language specifically in sociodramatic play and how teachers' language use is related to children's language productivity in sociodramatic play. Particularly, teachers' use of pretend talk is surprisingly under-estimated in the most recent relevant study. The purpose of this study is to describe how teachers use their language in sociodramatic play to increase children's language productivity that may further support children's language development. Using a mixed method design that uses both qualitative and quantitative analyses, this study seeks to describe (1) the variability of teachers' language productivity including lexical diversity, target word frequency and syntactic complexity, (2) different play styles in teachers' utterances in sociodramatic play and children's responsiveness to teachers' talk, (3) teachers' responsiveness to children's interests and children's responsiveness to teachers' talk, and (4) teachers' use of commenting, prompting, and questioning during sociodramatic play and children's responsiveness to teachers' talk. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]