In this case study, the author analyzes student writing produced in response to an SFL-informed analysis of excerpts from the Harry Potter novels as a means for evaluating the degree to which students adopted particular dispositions towards the texts and the ways these related to broader sociocultural discourses. Organized in a manuscript format, the dissertation is comprised of three articles, along with introduction and conclusion chapters. In the first manuscript, the author uses a heuristic informed the Legitimation Code Theory (LCT) dimension of Autonomy to conduct a review of relevant literature to related to the disciplinary literacy practice of literary response writing in subject English. The review discusses themes in the literature related to underlying principles of disciplinary literacy related to literary response writing in subject English including the semiotic and linguistic patterns in the genre of literary response. The study specifically focuses on knowledge bases in subject English, the disciplinary practices of experts, underlying principles of these practices, and the linguistic and semiotic patterns of the literary response genre. In the second manuscript, the author uses concepts from LCT and Systemic Functional Linguistics (SFL) to reveal the value positions constructed by 8th grade English language arts (ELA) students in essays produced in a critical literary analysis unit. After reading excerpts from two Harry Potter novels, students compared the main characters’ views on elvish enslavement as evidenced by the passages. This study uses axiological constellation analysis to explore the language choices in essays that constructed contrasting stances towards Harry's character and the representation of elvish enslavement in the texts. The study contributes to understanding how values are constructed in classroom writing and how these relate to broader sociopolitical discourses, with implications for critical praxis in subject English education. In the third manuscript, the author presents an analysis of the content knowledge in the same set of literary response essays. The LCT dimension of Autonomy is used to analyze the degree to which the meanings in the student responses related to the targeted content and purpose of the unit. The analysis reveals the ways student writers brought together information from the passages and from beyond the prompt and source texts to support their interpretations of the characters. The paper concludes with implications for designing instruction that supports students in recognizing and realizing the ways literary texts relate to broader cultural issues and facilitating the development of critical dispositions towards dominant discourses.