The relationship between pre-school teachers and the children in their classrooms directly influences the degree of success the children experience in school and in life. The emphasis on quality pre-K education in the U.S. has resulted in an increased need for highly qualified teachers who are capable of engaging in meaningful interactions with young children. An important component of high-level teacher-child interactions is the teacher's ability to model language for children as they acquire vocabulary and language context. This mixed-methods study was designed to examine the effectiveness of a professional development intervention designed to improve the quality of language modeling with pre-K teachers. Pre-kindergarten lead teachers were selected in three classrooms in each of two facilities. These teachers were surveyed on beliefs and intentions regarding their practice. They were given the opportunity to view and reflect on their use of language, then they were instructed on components of language modeling, followed by an opportunity to practice with further opportunities to review and reflect. Finally, they were interviewed on their perceptions of the intervention model. The teachers were video-recorded based on the professional development guidelines outlined in the "Classroom Assessment Scoring System Pre-K Manual" (Pianta, La Paro, & Hamre, 2008a). Teachers were instructed regarding ways of improving language modeling in their classrooms. Teachers reviewed their video-recorded sessions and evaluated their performance. Findings revealed improvements in the use of language modeling across all six participants. In two cases, teachers struggled with viewing themselves regarding language modeling and needed more coaching before they were able to view, reflect, and challenge themselves to improve their practice. In the interview portion of the study, all participants generally expressed positive impressions of the experience in the study and the need for including similar professional development in teacher preparation programs. [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.]