Despite general agreement about the importance of high-quality teachers, researchers, policy makers, and the public are unable to reach consensus on specific characteristics of secondary school teachers contributing to desirable educational outcomes. Policy makers are left with many questions surrounding what counts as a quality teacher—information that could be valuable in guiding policies regarding whom to hire, whom to reward, and how best to distribute teachers across schools and classrooms. Answers to these questions have potentially important implications for the efficiency and equity of public education for sustainable development. Failure by policy makers to define teacher characteristics linked to desirable education outcomes will be detrimental to educational quality trends in Kenya. This paper explores what the most important teacher characteristics are with special focus on qualification, subject matter knowledge and pedagogical content knowledge