Principal leadership is the key to successful implementation of mandated, high-accountability, teacher evaluation systems. Given the magnitude and complexity of change at the school level, understanding principals' perceptions, responses, and concerns is essential for effective change and support during implementation. Thus, research that considers both principals' concerns and their perceptions of implementation support contributes to both the scholarship and practice of leadership for change during accountability and reform. This multi-site, 3-year, qualitative study in a Southeastern state used the lens of Hall and Hord's (Implementing change: patterns, principles, and potholes. Pearson Education, Boston, 2015) stages of concern, from the concerns-based adoption model, to examine K-12 principal perspectives during implementation of new, rigorous, high accountability teacher evaluation policies. Findings from this study increase our understanding of the impact of implementation challenges and change processes on principals charged with leading externally mandated, high stakes innovations. When principals' knowledge and management concerns are insufficiently addressed, it is difficult for them to move to full and successful implementation. Findings have implications for superintendents, state policy-makers, university faculty in administration preparation programs, and researchers focusing on teacher evaluation, change, and education reform. In addition, this study adds to the literature by examining suburban and rural perspectives, complementing research focused on urban schools and districts.