Teachers are crucial to the success of our students. Yet many of them are leaving their schools and the profession every year, particularly in poorer, lower-performing schools. Several studies have attempted to identify why teachers leave and how to stem their turnover, but few have identified the quality of teachers who are departing. As in any profession, not all attrition is bad, but whether bad or good, it has financial ramifications. This brief explores the costs associated with teachers leaving the profession and their schools, the characteristics of those likely to leave, and what can be done to prevent unnecessary and costly turnover.