Typical high school ELA instruction fails to break the deeply rooted cycle of inequality in the United States. Within democratic and social justice traditions, a variety of theoretical frameworks promote equitable learning opportunities for nondominant youth. This dissertation synthesizes such frameworks to paint a more vivid picture of how to create high school English Language Arts (ELA) instruction for social justice and democracy than when frameworks are presented independently. The synthesis also highlights a need for a better understanding of how to design and evaluate education for social justice and democracy. Subsequently, the dissertation draws upon the wealth of knowledge on how to create equitable and effective ELA instruction to design high school ELA instruction through the lens of democracy, social justice, and Cultural Historical Activity Theory. A partnership between the author of this dissertation, a high school ELA teacher, and two of her 10th grade ELA classes (n = 58 mostly low-income, Latina/o students) completed the study in partnership. A Social Design Experiment provided the model for the process. The study provides an example of how to design ELA instruction that fosters democracy, social justice, and expansive learning within a public school classroom accountable to standardized processes and assessments. Contradictions and synergies between theoretical understandings of democracy, social justice, Cultural Historical Learning Theory, and standards based practices are brought to light to inform both theory and practice. Findings pose questions for educators to consider. Bounds on the potential for expansive learning in practice, inform the need for Cultural Historical Activity Theory to account for power to understand diversity in development within a system. The study also compares student development across fairly standardized instruction versus a Social Design Experiment. Students earn higher academic literacy scores, engage more actively in class, and form a more supportive community during the Social Design Experiment.