The Next Generation Science Standards hold promise for cultivating the diverse assets that students bring to science learning. One key asset in linguistically diverse science classrooms is translanguaging, or the use of one’s full communicative repertoire that transcends boundaries between named languages (e.g., Spanish and English) and modalities (e.g., linguistic and nonlinguistic). For teachers to harness this asset, they will need to hone their skills at formative assessment, specifically, how they listen and respond to students’ thinking communicated in ways that go beyond what has been traditionally privileged in science classrooms (e.g., written English). We refer to this as formative assessment from a translanguaging perspective. In this article, we illustrate how one fifth-grade teacher engaged in formative assessment from a translanguaging perspective in her dual language science classroom during a 3-day lesson focused on planning and carrying out an investigation of plant growth. Specifically, we illustrate how this teacher used multiple types of formative assessment that cultivated her students’ translanguaging and enabled her to stay closely attuned to students’ thinking as it developed. We close with recommendations for teachers interested in enhancing their formative assessment in linguistically diverse science classrooms.