To learn more about the early career patterns of beginning teachers, the National Center for Education Statistics (NCES) of the Institute of Education Sciences within the U.S. Department of Education undertook the Beginning Teacher Longitudinal Study (BTLS). The ultimate purpose of this report is to develop a strategy for the longitudinal analysis of the BTLS data that can be used to better understand teacher attrition, retention, and mobility. This report includes an analysis chapter that discusses the research purposes and results, and a chapter of conclusions and recommendations, followed by the tables of estimates. There are three research objectives addressed in this report. The first objective is to define the concept of a career path for beginning teachers that can be implemented with all waves of the BTLS. The second objective is to operationalize the assignment of a career path using this definition, i.e., examine methods for assigning career paths. To do so, this report investigates the methodological and analytic issues involved in analyzing the BTLS data longitudinally (i.e., across waves for individual teachers). The third objective is to investigate the best approach for analyzing the relationships between beginning teachers’ career paths and selected teacher and school characteristics. The following are appended: (1) Standard Error Tables; (2) Description of Variables; and (3) Methodology and Technical Notes. (Contains 24 tables, 1 figure, 4 exhibits, and 21 footnotes.) [This report was prepared for the National Center for Education Statistics (NCES) in collaboration with Westat, Inc.]