Many urban schools struggle to retain their best teachers because of challenging work environments, poor salaries, and ineffective school leadership. The additional requirements of the No Child Left Behind legislation for teachers to be highly qualified and the increased academic requirements of raising students to a proficient level in reading and mathematics mean that these schools face additional challenges to retaining teachers. Little research has been done on teacher retention in relation to NCLB in urban schools, but the few studies available have suggested that NCLB has had a negative impact on teacher morale and retention in urban schools. The research project was a paired case study that examined teacher retention in four urban schools, contrasting two schools that showed improvement under NCLB in terms of student achievement with two schools that did not show improvement. This study used human resource data, teacher and principal interviews, and school improvement plans to answer the following three research questions: 1) Does the teacher retention rate remain constant as schools improve? 2) Is there a pattern of teacher retention in improving schools? 3) What do improving schools do to attract, train, and retain teachers? The results showed that all schools had increased levels of teacher retention from the beginning of the study until the end. Improving schools had slightly higher rates of teacher retention, especially among teachers who were determined to be desirable. There was some evidence that as student achievement rates rose in improving schools, so did the rate of teacher retention. Lastly, the findings suggest that schools that were improving were also schools that embodied many of the factors that teachers are looking for in a school, including strong school leadership, positive working conditions, and other supports for teachers new and experienced, such as professional development and mentoring. This study has several limitations, such as a small sample size and a limited pool of human resource data. The findings have important implications for urban school districts that are trying to retain quality teachers. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]