This issue brief addresses the following questions: (1) How many teachers leave the profession in a year's time, and why? and (2) Are public school teachers more or less likely than private school teachers to leave the profession or move to different schools? Data were gathered from the National Center for Education Statistics 1987-88 Schools and Staffing Survey and the 1988-89 Teacher Followup Survey. Results suggest: (1) private schools regularly have to replace a larger percentage of their teacher work force than do public schools; (2) the combination of attrition and migration means an even larger proportional loss of teachers for the private sector in comparison with the public sector; (3) some reasons given for leaving the profession include better pay, other career opportunities, dissatisfaction with teaching as a career, family or personal move, health, pregnancy, or retirement; (4) teachers move to other schools for reasons such as reduction-in-force, lay-off, school closing, school reorganization, and reassignment; and (5) better salary and benefits offered in the public sector attract numerous private school teachers. For further information, three U.S. Department of Education reports are listed. (LL)