At the university level, introductory science courses usually have high student to teacher ratios which increases the challenge to meaningfully connect with students. Various curricula have been developed in physics education to actively engage students in learning through social interactions with peers and instructors in class. This learning environment demands not only conceptual understanding but also learning to be a scientist. However, the success of student learning is typically measured in test performance and course grades while assessment of student development as science learners is largely ignored. This dissertation addresses this issue with the development of an instrument towards a measure of physics learning identity (PLI) which is used to guide and complement case studies through student interviews and in class observations. Using the conceptual framework based on Etienne Wenger's communities of practice (1998), I examine the relationship between science learning and learning identity from a situated perspective in the context of a large enrollment science class as a community of practice. This conceptual framework emphasizes the central role of identity in the practices negotiated in the classroom community and in the way students figure out their trajectory as members. Using this framework, I seek to understand how the changes in student learning identity are supported by active engagement based instruction. In turn, this understanding can better facilitate the building of a productive learning community and provide a measure for achievement of the curricular learning goals in active engagement strategies. Based on the conceptual framework, I developed and validated an instrument for measuring physics learning identity in terms of student learning preferences, self-efficacy for learning physics, and self-image as a physics learner. The instrument was pilot tested with a population of Oregon State University students taking calculus based introductory physics. The responses were analyzed using principal component exploratory factor analysis. The emergent factors were analyzed to create reliable subscales to measure PLI in terms of physics learning self-efficacy and social expectations about learning. Using these subscales, I present a case study of a student who performed well in the course but resisted the identity learning goals of the curriculum. These findings are used to support the factors that emerged from the statistical analysis and suggest a potential model of the relationships between the factors describing science learning and learning identity in large enrollment college science classes. This study offers an instrument with which to measure aspects of physics learning identity and insights on how PLI might develop in a classroom community of practice. [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://www.proquest.com.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]