ABSTRACT In the landscape of U.S. education, the widespread adoption of the Next Generation Science Standards (NGSS) offers a unique vantage point for researchers to better understand teacher-, school- and classroom-level factors that advance reform initiatives in science classrooms. Addressing a gap in current knowledge, our study probes how secondary science teachers implement one dimension of NGSS-the science practices (SPs). Our data collection encompasses teacher interviews and meticulous observations of science lessons, coded for NGSS science practices (SPs) and inquiry-based teaching. Embracing a methodologically rich approach, our study employs both qualitative and quantitative data collection and analysis. Quantitatively, we analyzed 801 weeks of lessons taught by 56 secondary science teachers and found patterns in SP use. Selected high-quality science lessons were then spotlighted, providing examples of the quantitative findings, showcasing teachers use of SPs and inquiry-based teaching strategies. Through our analysis, we found that physical science subjects and participants from the Master of Arts in Science Teaching program demonstrated a higher average use of SPs compared to their life science and undergraduate program counterparts. When analyzing the use of specific SPs, we found that analyzing and interpreting data (SP4) and mathematical and computational thinking (SP5) emerged as noteworthy. This study’s findings carry implications for science teacher education and professional development programs, urging efforts to augment both the quantity of rigor of SP use in the secondary science classroom. Our research contributes insights that can inform strategies for the enhancement of science education alignment with the objectives set forth by NGSS