A critical challenge in urban science education is determining how to provide empowering science learning experiences for all students. In an effort to address the achievement gap in science education, I have focused on the concept of ownership, specifically when and how students gain ownership in science learning. This paper presents a teacher action research study with data collected over three school years and six 7th grade science classes in an urban middle school in New York City. The study addresses two questions: (1) Is it possible to foster student ownership in the context of school science and does this support students' engagement in science class? and (2) What are the classroom structures (physical, curricular, and pedagogical) that support students' cultivation of ownership? Two vignettes are used to illustrate how students fostered student ownership in the school science setting, how this supported students' engagement in science class, and how specific "ownership structures" supported students' cultivation of ownership. These vignettes make evident that it is possible to foster spaces of student ownership within the context of the formal science classroom that lead to increased and deeper student engagement. In addition, there are multiple dimensions to what students "own" within the context of the science classroom. (Contains 1 table and 2 notes.)