The increasing focus on educational accountability underscores the importance of understanding the factors that make some teachers more effective than others. Data from the Early Childhood Longitudinal Study of the Kindergarten Class of 1998-99 provide information on reading and mathematics development over the early school years and link students to their teachers. Thus, they permit us to investigate the relationship between teacher qualifications, instructional practices, and student achievement. This study addresses three research questions: To what extent are observable background characteristics and instructional practices of teachers associated with gains in reading and mathematics achievement of their students over the course of the kindergarten and first grade years? Are specific teacher characteristics and practices related to particular reading and mathematics proficiencies? How are the instructional practices of teachers related to their background characteristics? To answer these questions, meaningful measures of instructional practices in the teaching of reading and mathematics will be obtained using factor analytic techniques. Then measures of instructional practices will be related to teacher background characteristics in teacher-level regression analyses. Finally, student-level regressions will be used to assess the impact of teaching practices and teacher background characteristics on achievement in reading and mathematics. Specific proficiencies within each subject will also be examined in relation to the teaching measures. This study will provide many implications for policy. State legislatures and education departments, school boards, district administrators, and schools of education need information on the effectiveness of different teacher characteristics and instructional practices in order to make wise investments and allocations. In addition, the importance of studying young children widely recognized. Early teaching can be crucial to the future academic progress of children as well as to closing learning gaps between advantaged and disadvantaged children. Information that can lead to effective teaching strategies will provide policy makers with vital information that can improve the educational system. Given the focus on educational accountability based on test scores, it is of great importance that effective strategies be employed to increase learning by this measure. In addition, information on the types of techniques that relate to improving the attainment of specific proficiencies will provide much-needed information on a topic that is under-researched, particularly for children in this age group. Education is a major component of economic success and well-being, both physical and mental. Accountability policies in the US have focused on test scores as measures of learning. Factors influencing test scores-in particular, factors relating to teachers and schools-must be understood to create effective policies to improve learning. This study investigates the instructional practices and qualifications of teachers that promote reading and mathematics learning gains in young children.