The impact of No Child Left Behind (NCLB) mandated state science assessment on elementary teachers' beliefs about teaching science and their classroom practice is relatively unknown. For many years, the teaching of science has been minimized in elementary schools in favor of more emphasis on reading and mathematics. This study examines the dynamics of bringing science to the forefront of assessment in elementary schools and the resulting teacher belief and instructional shifts that take place in response to NCLB. Results indicated that teachers' beliefs about teaching science remained unchanged despite policy changes mandated in NCLB. Teacher beliefs related to their perceptions of what their administrators and peer groups' think they should be doing influenced their practice the most. Most teachers reported positive feelings and attitudes about science and reported that their students had positive feelings and attitudes about science; however, teachers reported teaching science less as a result of NCLB. Implications for elementary science education reform and policy are discussed.