This dissertation is rooted in three strands of scholarship: translingual approaches to writing (Horner et al., 2011), social design-based experiments (Gutierrez & Vossoughi, 2010) as a subset of participatory design-based research (Bang & Vossoughi, 2016), and the Learning on the Move framework centering embodied and mobile epistemologies (Marin et al., 2020). In this study, I partnered with a sixth-grade teacher at a Title I elementary school in a mid-size suburban district in the Pacific Northwest to design and implement more just writing pedagogies in a school setting in the context of shifting school contexts during Covid-19. Drawing on translingual approaches to writing, which posit that language practices are inherently social, fluid, and emergent, I worked with the teacher to better understand translingual approaches to writing and situate his daily teaching dilemmas for writing instruction within translingual ideologies. We also regularly collaborated to co-design learning environments for writing that centered young people's linguistic repertoires and aimed to desettle the sedentarist traditions of writing classrooms. We ultimately co-designed a novel-based unit in spring of 2022 that attended to questions of place, movement, language, and identity while also asking students to draw on their related experiences, including their experiences of writing. Findings from the first article of this dissertation highlight how situating here-and-now dilemmas within aspirational ideologies can open possibilities for the design of writing environments that center translingualism, relationality, and personal becoming, as opposed to themes of competence and competition in writing practice. The second article in this dissertation highlights how framing young people as language architects can set the stage for meaningful participation in school-based writing activity. The last article proposes a blended conceptual framework drawing on translingual approaches to writing and the Learning on the Move scholarship as creating possibilities for designing more just writing environments in schools. This dissertation has implications for studies of and designs for writing and learning that aim to resist settled notions of school-based writing 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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]