DescriptionPurpose/research question. Reading comprehension has been identified as one of the most pressing issues in literacy education. To date, most of the literature focuses on student learning and not on how to help teachers improve their reading comprehension instruction. This mixed methods case study examined how three 1st grade teachers responded to a professional development intervention aimed at improving reading comprehension practice. The research question guiding the study was: What happens when a professional development initiative engages teachers to scaffold students to use more explanations, predictions, and inferences? This question was examined in two ways. One line of inquiry focused on the teachers and how the professional development impacted their reading comprehension instruction. The second line of inquiry sought to examine the effects of the professional development on a small group of students’ reading comprehension. Methodology. The eight-week professional development intervention took the form of a professional learning group where the teachers and I met over 8 weeks for 30-minutes to explore strategies to encourage student thinking about text. To examine the process and impacts of the professional development intervention, I conducted interviews, observations of teachers during the professional development sessions and in their classrooms, and collected various documents including lesson plans and weekly reflections. To ascertain the impact on students, pre and post-assessments were given to six focal students and all classes were given the Gates-MacGinitie Reading Test. In keeping with a case study design, multiple procedures were used to collect and analyze data. The data were transcribed, coded, and analyzed in order to describe the professional development intervention, each teacher’s response to the intervention, and students’ change in comprehension. Findings/Implications. Each teacher’s practice was found to change over the course of the 8 weeks of the intervention. The observed and reported changes were mediated by experience, knowledge of reading comprehension, and the design of the professional development. The findings of the study suggest that creating teacher professional learning communities around complex topics requires careful consideration of what it means to partner with teachers and how to use time as a resource that affords opportunities for teacher learning.