Teacher education programs are responsible for preparing science teachers for today's culturally and linguistically diverse classrooms, which includes preparing them to support students' science learning and language development. Given the rapid growth in linguistic diversity across the country, science teacher preparation for English learners, referred to here as emergent bilinguals, is particularly critical. Although research-based pedagogical practices have been established for both science learning and language development, the fields remain separated in preparatory programs, which makes it unlikely that teachers will merge the 2 in future practice. To date, research has begun to explore professional development efforts with in-service teachers focused on science education for "emergent bilinguals," but studies involving preservice science teachers are scant. Working within a sociocultural paradigm, this single-case study uses narrative methods to explore the following question: How does field-based teacher education promote and influence the development of professional expertise for teaching emergent bilinguals in secondary science classrooms? Analyzing data collected over 2 years, we present findings from a secondary science teacher candidate's experiences across a field-based teacher education program that prioritizes understandings, knowledge, and skills for emergent bilinguals. We discuss implications for science teacher educators seeking to design effective field-based programs that prioritize emergent bilinguals.