This study examined the reasons that mathematics teachers enter the teaching profession, and compared those reasons with the reasons for leaving the teaching profession. Participants in a national study were surveyed and interviewed, with results broken into categories of gender, age, ethnicity, and region of the country. Results indicated that mathematics teachers enter the teaching profession because of a desire to work with young people, a love of mathematics, and wanting to make a difference. Stated reasons for leaving the teaching profession center on low salary, teacher blame, and lack of administrative support. The implications of this study are important in the preparation of new teachers, and in maintaining a pool of qualified mathematics teachers for the future. (Contains 7 tables.)