I conducted case study research on five third-grade teachers to go "beneath" the appearance of best practices and understand what helps students make the greatest literacy achievement. I asked principals and reading experts to complete a best practices rubric and then selected the two highest scoring teachers from three schools. I observed at least two consecutive days of reading instruction in the fall and spring and conducted interviews in the beginning of the year and after each observation. I collected beginning and end-of-year standardized (MAP) and oral reading data. After analyzing the data, I wrote classroom portraits that represented my understandings and then looked for patterns across classrooms. I found that (a) in the classrooms of teachers who shared five or more of the identified characteristics (management, agentive talk, naming beliefs, use of practices relative to beliefs, focus of instruction, and focus and use of assessments), 60% or more of the students met or exceeded the MAP target RIT scores and had high text reading growth on Dominie; (b) teachers with fewer characteristics had lower reading growth on the Dominie; (c) a low number of characteristics did not predict MAP; (d) students who met targeted growth on MAP were not necessarily able to handle complex texts; and (e) there were differences in achievement between workshop-and basal-modeled classrooms. These findings have implications for instruction and assessment and suggest that expanding the definition of "best practice" classrooms might better allow the field to predict achievement. [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.]