Teachers are central to providing high-quality science learning experiences called for in recent reform efforts, as their understanding of science impacts both what they teach and how they teach it. Yet, most elementary teachers do not enter the profession with a particular interest in science or expertise in science teaching. Research also indicates elementary schools present unique barriers that may inhibit science teaching. This case study utilizes the framework of identity to explore how one elementary classroom teacher’s understandings of herself as a science specialist were shaped by the bilingual elementary school context as she planned for and provided reform-based science instruction. Utilizing Gee’s (2000) sociocultural framework, identity was defined as consisting of four interrelated dimensions that served as analytic frames for examining how this teacher understood her new role through social positioning within her school. Findings describe the ways in which this teacher’s identity as a science teacher was influenced by the school context. The case study reveals two important implications for teacher identity. First, collaboration for science teaching is essential for elementary teachers to change their practice. It can be challenging for teachers to form an identity as a science teacher in isolation. In addition, elementary teachers new to science teaching negotiate their emerging science practice with their prior experiences and the school context. For example, in the context of a bilingual school, this teacher adapted the reform-based science curriculum to better meet the unique linguistic needs of her students.