No one would disagree that young children's literacy learning is of primary importance in the early childhood years. One of the best ways for children to learn oral language is through play. However, many teachers view play as a child's work and not as a space where the teacher can support children's literacy learning. This study investigated the implementation of a professional development initiative that sought to help teachers at a preschool become more intentional in their interactions with children during play. The overall question framing this qualitative study was: "What happens when I implement a PD program focused on improving the teaching of vocabulary and oral language during playtime?" This question was examined in two ways. One line of inquiry focused on what the PD initiative looked like in action. The second line of inquiry focused on three teachers' literacy beliefs and practices of playtime before, during, and after the PD intervention. The sample for this study was comprised of three teachers who participated in a 3-month professional development initiative. Data collection consisted of observations through the administration of the Supports for Early Literacy Assessment (SELA) (Smith, Davidson, Weisenfeld & Dennis, 2001) and through the use of field notes. Teacher-generated reflections were completed after each PD workshop session. The teachers were also interviewed before and after the PD. An analysis of the PD was completed using the theoretical framework to capture specific aspects of the curriculum. To provide a descriptive portrait of each teacher a mini case study analysis was completed. It was found that the teachers' responses to the professional development were mediated by their beliefs about teaching, play, and literacy development. Effective aspects of the professional development included the use of protocols and the opportunity to work together. In order to have more of an impact on teachers' practices the professional development model requires revisions in timing of delivery and curriculum content as well as the addition of a coaching component. The findings of this study have also been used to inform adoption of a new, more play-focused curriculum at the preschool. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]