Disability labels and other social categories in school arise out of an educational system which attributes learning problems, perceived weaknesses, and academic failure to individual students. Instead, this dissertation investigates how learning problems are produced and reinforced through cultural practices. Through a two-year, cross-context ethnography, I examine the personal, interpersonal, and institutional storylines which make disability labels relevant in certain contexts and shape whether students can fully participate. This approach considers how every engagement, relationship, and activity across different social contexts has the potential to change how students see themselves and are viewed by others. These experiences contribute to a continuous, dynamic process of identity development. By studying youth identity, I aim to understand how students' stories unfold and are influenced by disability labels and how their encounters across contexts continue to shape their future life trajectories. By following 12 youth with disabilities in traditional classroom settings, informal environments, and everyday home activities, I consider the following: (1) How do youth with disabilities develop identities as learners through their experiences across social contexts? (2) How do perceptions of ability and expectations for success influence this process of identity development? To clarify how youth experiences are embedded in cultural phenomena, I use Harre's positioning theory to analyze video-recorded observations and interviews and examine how different storylines shape how youth think of themselves as learners. In Part I, I describe the contexts I encountered and how my interactions with students shaped my methods, conceptual framework, and analytic process. The five chapters in Part II focus on seven case studies of youth with disabilities in academic classrooms, alternative school contexts, debate team, writing and gaming contexts, and home life. Each case considers how students are positioned through their interactions with others and how perceptions of ability can encourage or constrain participation. These chapters are intertwined with interludes which trace the case of Anthony Gustafson, providing an in-depth picture of one student's experience with disability. The final section concludes with a discussion of the lessons learned from each student, which help inform future questions and areas for educational change. [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.]