Low-income urban schools that have chronic student underachievement have championed instructional coaching as an effective education reform strategy. Studies have shown that instructional coaching can be a promising approach for teacher professional development aimed at building educators' capacity to use student data to inform literacy instruction and increase student performance on standardized reading assessments (Bertrand & Marsh, 2015; Huguet, Marsh, & Farrell, 2015; Marsh, McCombs, & Martorell, 2010). The purpose of this qualitative case study was to better understand how teachers in a low-performing urban elementary school serving mostly minority students perceived student assessment, data use, and literacy instruction after participating in an externally funded professional development initiative. Of particular interest was exploring how instructional coaching and a professional learning community (PLC) led by an external literacy consultant influenced teachers' perceptions of collaborative data use and literacy practices implemented in the school. The findings from this study suggest that during the three-year coaching project, teachers perceived an increased focus on using benchmark and progress monitoring assessments to measure student performance and progress with developing reading skills. Additionally, teachers experienced mounting pressure from school leadership to use data to improve student learning outcomes and to conform to a preferred approach to literacy instruction. Although there was increased teacher dialogue about student literacy data within the PLC, data conversations mainly focused on low-performing students who did not meet reading benchmarks, which resulted in assigning students to reading groups for targeted interventions. Data analysis revealed that teachers perceived student progress toward meeting mid-year and end-of-year literacy goals as being an outcome of the instructional coaching they received and the small-group literacy instruction they implemented in their classrooms. [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.]