Systemic changes to curriculum are an inevitable part of education; however, understanding how teachers and administrators perceive their responsibilities in implementing district-mandated changes to curriculum is unclear. The purpose of this qualitative case study was to determine teachers' and administrators' perceptions related to their responsibilities in effective implementation of district-mandated changes to curriculum. The conceptual framework for this study was change theory to explore how teachers and administrators process district-mandated changes to curriculum. Data were collected through semistructured interviews with eight teachers and seven administrators who have implemented district-mandated changes in a public school in the mid-Atlantic region of the United States. Data were analyzed through a priori coding and thematic analysis resulting in five themes (a) communication, (b) student centered, (c) collaboration, (d) support, and (e) adapting to the mandated change. The teachers and administrators who participated in this study shared they believe they both have the responsibility of understanding the district-mandated change to effectively implement the change. To implement change that challenge teachers' and administrators' current beliefs, participants of this study felt it was important to collaborate and share ideas. The findings from this research have potential implications for positive social change in that they may be used to develop strategies for collaboration and collective input when implementing district-mandated changes to curriculum, in support of student 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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]