Achievements of educational reform advantage constructivist understandings of teaching and learning, and therefore highlight a shift in beliefs of teachers and apply these perceptions to the real world. Science teachers' beliefs have been crucial in understanding and reforming science education as beliefs of teachers regarding learning and teaching science impact their practice. The purpose of this study was to compare US and Turkish science teachers' beliefs about reformed learning and teaching science. As an instrument, we used Beliefs about Reformed Science Teaching and Learning (BARSTL) to collect and measure the teachers' beliefs regarding teaching and learning science education. We used an independent-sample t-test to analyze Turkish and American science teachers' beliefs about reformed learning and teaching science. In total, 38 science teachers from the US and 27 science teachers from Turkey participated in this study. Results showed that US science teachers' beliefs about reformed learning and teaching science are statistically higher than Turkish science teachers. The results of this study also indicated that although American and Turkish science education aim similar constructivist views on learning and teaching science, American science teachers hold more reformed beliefs in science teaching and learning than their Turkish colleagues.