Efforts to increase time and opportunity to learn science in urban, underserved elementary schools have focused on improving teachers' science instruction through school-based professional development. This dissertation examined how the social justice science teacher identities of two co-teachers of color developed and shaped while participating in a yearlong, school-based professional development in science. It also examined how two teachers of color and one White teacher activated the human and nonhuman resources provided by the science professional development to transform or maintain their science teaching practices and understandings. The theoretical frameworks included situated perspective of learning, social justice science teacher identity, social structures as schemas and resources, and the relationship between structure, agency, and science teacher identity. Data collection methods included interviews, teacher questionnaires, researcher field notes, and teacher-created documents, such as science slides and student handouts. Data analysis methods are drawn from grounded theory and multiple case study. The findings suggest that teachers' experiences, orientations, views, existing identities as teachers and in relation to science, as well as their philosophies of students and learning all influenced how they participated in the science professional development, the meanings they constructed through participation, and the ways their teaching practices changed. Teachers at different phases in their careers also wanted and needed different kinds of PD supports. The findings suggest that science teacher educators who are developing science professional development models and workshops should be cognizant of all of these influencing factors on teacher learning and provide differentiated PD activities to support the various learning needs, identities, and personal and professional goals of elementary teachers. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]