One of the most pressing issues facing policymakers is how to staff classrooms with a stable teaching force responsive to complex student needs and the growing demands of the knowledge economy. Recurrent teacher shortages are a function of both declines in entrants to teaching and high rates of teacher attrition, especially in low-income schools. This turnover is costly, and undermines student achievement and school improvement efforts. A better understanding of why teachers enter and leave the profession, and what might encourage them to stay or return, is critical to improving the educational opportunities for all students, especially those attending the most disadvantaged schools. This paper reviews an extensive body of research on teacher recruitment and retention, and identifies five major factors that influence teachers' decisions to enter, stay in, or leave the teaching profession, generally, and high-need schools, specifically. Those factors are: (1) Salaries and other compensation; (2) Preparation and costs to entry; (3) Hiring and personnel management; (4) Induction and support for new teachers; and (5) Working conditions, including school leadership, professional collaboration and shared decision-making, accountability systems, and resources for teaching and learning. Based on this review and analysis, the authors outline local, state, and federal policies, grounded in research, that can help to recruit and retain excellent teachers, especially in the highest-need schools. [For the research brief, see ED606766.]