This ethnography explores the locally defined and culturally negotiated roles and responsibilities of elementary science specialists (ESS) in three New York City schools. Drawing upon interviews with ESS, classroom teachers, and building administrators, this study examines the roles and interactions of ESS with regards to instruction, support, and leadership as analyzed through a distributed leadership lens. The implementation pattern matched the characteristics of the science as a special model of elementary content specialization. While lacking specific qualifications or clearly defined roles, ESS were primary, exclusive, or supplementary providers of science instruction. Urban ESS leveraged relationships with various classroom generalists and faced challenges in navigating science leadership responsibilities such as curriculum coordination, communication, and support of classroom teachers.