This dissertation builds from previous studies of social annotation in first-year composition to link social practice theories of literacy with technologically mediated social annotation practices. Using a design-based research framework, I consider how recent developments in social annotation tools allow instructors and students to share the digital margins of the text for broader and more frequent study of student reading. Previous research supports widespread acknowledgment of the importance of reading in the writing classroom. However, many instructors remain unsure of how to teach reading in the writing classroom. This study uses Brandt's theory of accumulating literacies to explain this challenge and accounts for the cognitive, social, and material nature of literacy learning in a proposed social annotation intervention. I ask first, how can writing instructors effectively design social annotation embodiments to bridge institutional demands and student needs and experiences in the context of an FYC course? And second, how do social annotation design embodiments shape the ways students read strategically, interact with other readers, and take up annotations in a first-year composition course? The final research question explores how social annotation processes contribute to the development of metacognitive and social awareness and affect writing in a first-year composition course. Over two terms in a first-year writing class, I designed and tested social annotation as an educational intervention. I constructed data to document my teaching practice and student work, including students' social annotations, think-aloud protocols, and summative assessments and reflections for each unit of instruction. I then compared students' annotations and sense-making using a grounded theory framework to consider the relationships between my design for social annotation and student learning. Quantitative measures of significant variance and correlations support this qualitative description of how social annotation functions as an intervention. Findings suggest that model texts, annotation instructions, and grouping strategies are three key areas for pre-annotation design. Post-annotation design elements provide opportunities to extend student and instructor learning. Analysis of the learning outcomes suggests that overall social annotation supported participants' abilities to read and annotate like a writer who is aware of the social relationship between a writer and readers. Fewer students recognized the importance of reading and annotating in a community of writers even when the intervention design emphasized social interaction. This study illustrates how older literacy practices linger even as new literacy practices are introduced, resulting in overlapping accumulating literacies. Implications for addressing these overlapping, literacies for first-year composition instructors are discussed. Contributions to design-based research include a backward design approach to developing a conjecture map that begins with the proposed learning outcomes and explicitly accounts for the context in a conjecture mapping process to enable transfer of findings to new contexts. [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/en-US/products/dissertations/individuals.shtml.]