This ethnographic study investigated the implementation process of mathematics curriculum initiatives designed to improve student achievement in a test-driven accountability environment. The research focused on complex factors within the school contextual environment influencing implementation and student achievement specifically, leadership; school culture; and teacher's attitudes, beliefs, and concerns. The mixed methodology included statistical analysis of changes in state assessment scores of eighth grade students over a two-year period in four middle schools. The larger qualitative component involved the researcher, as participant observer, collecting data on implementation levels, leadership characteristics, elements of school culture, and individual teacher's attitudes, beliefs and concerns. Informal interviews and observations of 26 mathematics teachers and school leaders were conducted over a period of 12 weeks. In addition, teacher Concerns Profiles were developed from the Stages of Concern Questionnaire (Hall & Hord, 2001). The resulting profiles of school culture, leadership elements, and teacher's attitudes, beliefs, and concerns were analyzed for patterns and themes related to implementation levels and changes in state assessment scores. Findings indicated a relationship between: (1) the level of implementation of the curriculum initiative and improvements in state assessment scores and (2) a teacher's Stage of Concern and their level of implementation. Additionally, the study identified potential influences on teacher's attitudes, beliefs, and concerns including (1) the Form of instructional team/grade level subculture; (2) the support of team/grade level leaders; (3) the depth to which overall school leadership supports the curriculum initiatives; and (4) the availability of time to implement the initiatives. The conclusions confirm existing research on the influences of individual teacher's attitudes, beliefs, and concerns classroom practice while underscoring the importance of distributed leadership and collaborative instructional cultures in schools if improvement initiatives are to have the intended impact on student achievement. The study adds clarity to the complex set of factors within a school that can facilitate or impede successful implementation of curriculum initiatives designed to improve the achievement of all students. Appendixes: (1) Overview of Data Collection Procedures; (2) Stages of Concern Descriptions; (3) Stages of Concern Questionnaire and Scoring Guide; (4) School Culture Observation/Interview Framework; (5) Leadership Observation/Interview Framework; (6) Level of Use Framework; (7) Informal Interview Primer Questions; (8) Field Note Template for Interviews and Observations; (9) Preliminary Coding Categories; (10) Overview of Data Analysis Procedures; (11) District Permission to Conduct Research Study; (11) Invitation to Participate in Research Study; (12) Informed Consent Form; (13) Copyright Republication Permissions; (14) Stages of Concern Profiles; (15) School PSSA Profiles 2004; (16) School PSSA Profiles 2005; (17) School Level Assessment Score Comparison; (18) School A: Teacher/Group Level Assessment Score Comparison; (19) School B: Teacher/Group Level Assessment Score Comparison; (20) School C: Teacher/Group Level Assessment Score Comparison; and (21) School D: Teacher/Group Level Assessment Score Comparison.) (Contains 15 tables and 25 figures.) [Ph.D. Thesis, Drexel University.]