The Next Generation Science Standards (NGSS), are the biggest change to American science education since the National Science Education Standards (NSES) were published. While inquiry was central to the NSES, science assessment largely addressed factual knowledge acquisition.The NGSS represent a significant practical change for teachers as they mark a return to the ideals specified in the National Science Education Standards (NSES) and Benchmarks for Science Literacy. The purpose of this explanatory sequential, mixed-methods study was to identify and compare the factors that influenced high school science teachers' receptivity to the curricular shifts necessitated by the adoption of the NGSS. The survey data identified three factors as significant predictors of teacher receptivity: teachers' non-monetary cost-benefit analysis, alignment between the NGSS and their current teaching style, and concerns about student readiness. To understand how these factors operate in the classroom, both receptive and nonreceptive teachers were interviewed. In terms of cost-benefit analysis, all teachers agree that time is a significant cost. This includes the time it takes to adapt lessons to the NGSS, and the time it takes to teach in a way that integrates the three parts of the NGSS which are the practices of science and engineering, the crosscutting concepts, and the disciplinary core ideas. In terms of alignment between their teaching style and the NGSS, teachers talked about the lack of examples of what NGSS-aligned instruction looks like and the dearth of accessible high quality professional development. Finally, concerns about students' readiness focused on both inadequate preparation for college-level science coursework and deficits in science instruction in the lower grades.