The most fundamental reason why teachers are evaluated is because public schools take public money, and the public has a right to expect high-quality teaching. But there are two more basic purposes: (1) to ensure teacher quality; and (2) to promote professional development. The challenge is merging these two purposes of teacher evaluation. Educators need to create procedures that yield valid and reliable results--that is, that satisfy the legitimate demands for quality assurance while promoting professional learning. In truth, the demands are somewhat different. A system to ensure quality must be valid, reliable, and defensible (these are "hard sounding" qualities) whereas a system designed to promote professional learning is likely to be collegial and collaborative and much "softer-sounding." Until recently, educators' attempts at merging quality assurance with professional learning have taken the form of enhancing evaluators' skills using techniques like clinical supervision and cognitive coaching. But these skills are insufficient. The profession is better served when the requirements for these two purposes are embedded in the design of the systems themselves. Abundant evidence from both informal observation and formal investigation indicates that a thoughtful approach to teacher evaluation--one that engages teachers in reflection and self-assessment--yields benefits far beyond the important goal of quality assurance. Such an approach provides the vehicle for teacher growth and development by providing opportunities for professional conversation around agreed-on standards of practice.