Using findings from a 4-year research and development effort, we propose an updated model of sheltered instruction for science classrooms that leverages the opportunities provided by the Next Generation Science Standards (NGSS) to better support multilingual learners in middle and high school science. Using data from teacher implementation logs and interviews, we examine how secondary grades science teachers' participation in our professional learning framework and subsequent enactments of an initial set of project instructional practices led these teachers to articulate nuanced and strategic adaptations to the initial practices to better meet the needs of the multilingual learners in their classrooms. We found that teachers moved away from implementing sheltered instruction practices based on general principles or formal classifications, such as students' English language proficiency level, instead taking a more nuanced approach to adopting, adapting and rejecting practices based on perceived needs, assets, and personal knowledge about individual multilingual students in the specific disciplinary context of science. Based on this analysis, we conceptualize and refine what we now see as a new and exploratory set of Next Generation Sheltered Instruction practices for integrating science and language to support multilingual learners in secondary science classrooms in the age of the NGSS.