Despite its potential to capitalize on children's inherent curiosities about their worlds around them, elementary science is typically taught with either a transmissive model in which students are passive recipients of scientific knowledge or a conceptually incoherent model of disconnected science activities with little scientific knowledge construction or sense-making. This is a problem for all students, and it is particularly problematic for students from marginalized communities who have more limited opportunities to experience authentic science inquiry outside of the classroom than their White, native English-speaking, male peers. In this dissertation, I adopt an expansive definition of equity in order to foreground the ways in which science can be taught which broaden traditional norms of what counts as knowing and doing science in elementary classrooms to be more inclusive of students' diverse cultural and linguistic backgrounds. In so doing, students have increased opportunities to engage in scientific sense-making. Specifically, I am interested in the affordances of teachers' responsiveness during science lessons towards these expansive equity outcomes. I explore both teachers' disciplinary responsiveness-that is, teachers' responsiveness to students' scientific sense-making-as well as teachers' equitable responsiveness-that is, teachers' responsiveness to students' cultural repertoires of practice, linguistic resources, or racialized life experiences. My central research question is to investigate how teachers navigate these two approaches to responsiveness-disciplinary and equitable-in their science teaching. I conducted a qualitative embedded multi-case study with two urban elementary teachers. One teacher taught in a building serving a predominantly emergent bilingual Arab American Muslim community, and the teacher is also Arab American Muslim and bilingual. The other teacher taught in a school serving a predominantly emergent bilingual Latinx community, and the teacher is White and monolingual. I worked with each teacher over seven weeks, conducting pre- and post-interviews, observing science lessons, and debriefing after many of their lessons about how they went, decisions they made, students' engagement, and their plans moving forward. I conducted multiple rounds of coding on transcriptions of the audio-recorded conversations, selected compelling lessons from the video-recordings for further analysis, and constructed narratives around select lessons which illustrated moves made by teacher participants to answer my research question. Findings from these cases suggest that the foregrounding of building relationships with students is a critical part of what it takes to be equitably responsive in science teaching. Also, taking into consideration a teacher's biases when interpreting her science teaching practices is crucial for gaining a more complete understanding of her responsiveness. In conclusion, I propose a model of Equitable Disciplinary Responsiveness which merges the two approaches to responsiveness into one framework for future use in research and teaching with elementary science teachers. Gaining a better understanding of how equitable disciplinary responsiveness can be enacted in elementary science classrooms is one small step in a broader effort to move towards more equitable science teaching and learning for students.