The purpose of this action research study is to identify, implement, and evaluate best practices in reading improvement in third grade at Greenleaf Upper Elementary (pseudonym) in support of a process of continuous improvement. The study followed a mixed methods design. The student participants in this study were 47 third grade students who performed in the bottom quartile in reading. Quantitative data of third grade students' test scores were analyzed from the school's STAR reading program. The students' cut scale scores from 2016-2017 in the STAR reading program were compared to their cut scale scores from 2017-2018 in the STAR reading program. Qualitative data was analyzed from teacher interviews held by the researcher. The ten teacher participants in this study were third grade teachers at the assigned school. The interviews were conducted in two phases. Phase one interviews were held at the beginning of the study. Phase two interviews were held at the end of the study. Professional development was used to determine if student achievement in reading would increase at the assigned school. Third grade teachers completed face-to-face as well as online training in the Language Essentials for Teachers of Reading and Spelling (LETRS). Third grade teachers implemented the LETRS strategy to the students who performed in the bottom quartile in an effort to increase student achievement in reading. Due to the implementation of a new core reading program at the assigned school during LETRS implementation, a determination could not be made if the LETRS strategy or the new core reading program (Collaborative Classroom) attributed to the increase in students' yielded growth upon analysis of the students' STAR reading cut scale scores. [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/en-US/products/dissertations/individuals.shtml.]