This study examined the role of K--12 science teachers' understandings and perceptions of the Next Generation Science Standards, implementation of the new standards in the classroom, and potential barriers to implementation as reform stakeholders had envisioned. Grounded in the relevant literature and working from the Teacher-Centered System Reform framework, this study employed a quantitative approach to data collection. The TCSR Model framed this study by linking teachers' demographic and professional profile, teaching experience, professional development, district-level, school-level, and classroom-level contexts and illuminates the dynamic effect the factors have on teachers' thinking and their practice. The study recognizes teachers' knowledge and beliefs, their personal backgrounds, and the contextual factors that influence their practices and provides a context for improvement built from the interrelatedness of the varying perspectives of reform.