This mixed-methods study examined Grade 4 students’ growth in two types of civic competencies—argumentation skills and disciplinary thinking, and how civic competencies interweave and co-develop over an academic year in the context of an interdisciplinary social studies curriculum called Digital Civic Learning (DCL). A total of 106 fourth-grade students (38.7% girls) and 6 social studies teachers participated in the study. Quantitative evidence indicates that students in the DCL curriculum significantly improved in their argumentation skills (argument-counterargument integration, claim-evidence integration) and disciplinary (...) thinking. These civic competencies became more strongly associated with each other by the end of the curriculum. Multiple case studies revealed how two students synergistically applied their evolving argumentation skills and disciplinary thinking through distinct learning pathways. These results paint a complex picture of the development of students’ disciplinary thinking and integrating of argumentation skills, and the role of the curriculum in fostering the concurrent development of these civic competencies. Findings align with our overarching assumption that, through collaborative discourse and immersive learning about complex social issues, students can leverage their disciplinary thinking during argumentative social interactions, grappling with solutions and seeking common ground; continuous discourse among peers further enhances argumentation skills while honing disciplinary thinking. This study bridges the research-practice gap by providing evidence for the co-development of argumentation and disciplinary thinking within social studies classrooms. Our findings underscore the importance of inquiry-based learning, aligning with the College, Career, and Civic Life (C3) Framework, fostering critical civic competencies, and empowering students to actively participate in democratic processes. Particularly in this digitalized society, DCL emerges as a promising approach to integrate disciplinary thinking and argumentation skills across both physical and digital environments, fostering informed and active citizenship among students. (shrink)