This study, using qualitative, multiple case methodology, examined four middle schools within a Local Education Agency (LEA) in eastern North Carolina to determine whether the implementation of key middle school features; (a) interdisciplinary teaming, (b) flexible scheduling, (c) advisor/advisee relationships, and (d) an integrative, exploratory and challenging curriculum had an impact on middle school student achievement outcomes when implemented to the fullest extent. Descriptive data was gathered and analyzed, first by individual cases and then collectively to determine the level of implementation. Findings revealed implementation scores ranging from 6.5 to 8.1 on a scale from four to twenty which suggested that the key features were implemented within the selected schools. However the low implementation scores also indicated that the features were not fully implemented. When implementation scores were compared to achievement data, rival explanations for student achievement emerged featuring (a) socioeconomic effects, (b) school size effects, and (c) the effect of community dynamics. [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.]