Current research and declining test scores indicate that changes in educational practice are required for successful implementation of the Common Core State Standards for Mathematics (CCSSM). Using a constructivist change theory framework, this grounded theory study explored the experiences 6 purposefully selected, experienced teachers at an Upstate New York school district had related to the implementation of the CCSSM. The research question investigated the experiences that educators had related to implementing the CCSSM and the accompanying New York State mathematics modules. Observation notes, interview transcripts, and teachers' journals were collected and analysed simultaneously through coding, constant comparison, theoretical sampling, and memoing. The core concern that emerged was the lack of alignment between the standards and the curriculum being used to teach them. This lack of alignment was related to oversized and repetitive lessons, as well as the de-emphasis on teaching the mathematical practice standards that are a large part of CCSSM. These factors caused teachers to invest large amounts of time re-writing curriculum. Findings suggest that administrator-supported adaptive professional development is required to strategically address experienced educator needs while allowing for educator autonomy in curriculum design. The project, an adaptive professional development plan, will support experienced educators as they enact modifications to curriculum in order to address the changes in teacher practice and student learning that are needed to align instruction with CCSSM . This project can be used on a wider scale and can contribute to the knowledge base of implementation models for educators to enact the changes in instruction necessary to improve student mastery of the CCSSM.