This article examines the need for 21st Century Schools to address and manage all of their employment needs—e.g., hiring, evaluation, corrective action—as part of an integrated approach. During the past 18 months, ISM has been engaged in an intensive study of the needs of the 21st Century School.1 With specific regard to faculty, we believe that to thrive, schools will need to: measure teacher effectiveness on an ongoing basis (such as through annual evaluations); establish annual career-long improvement plans that invest in each teacher’s strengths;2 and hold ineffective teachers accountable.3 These objectives are best achieved by taking an active, integrated approach for engaging, managing, and developing the school’s faculty. Our model, called Comprehensive Faculty Development, is a mission-based series of interrelated activities through which the Head and her deputies systematically work to attract, develop, evaluate, reward, and retain teachers who deliver the mission to students with excellence.4