First-Year Composition (FYC) pedagogy has long oscillated between emphasizing rhetorical agency, reflection, and purpose on one hand, and genre knowledge, modality-use, and technical form on the other. Across the field’s pedagogical movements, these dimensions are often intertwined in practice, yet the instructional logic coordinating rhetorical decision-making with modal production has not been explicitly named. As a result, the relationship between rhetorical agency and modality-use remains implicit rather than systematically articulated. Identifying this interdependence as a persistent tension in writing instruction, this dissertation proposes a dual framework that names, theorizes, and operationalizes these two concepts as the foundation of FYC pedagogy. Because this tension reflects an absence of explicit conceptual framing rather than ineffective pedagogy, the study turns to Naming What We Know: The Threshold Concepts of Writing Studies by Elizabeth Wardle and Linda Adler-Kassner, which frames threshold concepts as transformative understandings that reshape how writing is taught and learned. Building on Wardle and Adler-Kassner’s insight that writing is both an activity and a subject of study (15), this dissertation identifies the interdependence of rhetorical agency and modality-use as a threshold concept for composition pedagogy. By naming this duality, the framework provides a lens for designing, sequencing and assessing multimodal instruction, while the dual framework refers to the curricular model itself, including its design principles, instructional units and pedagogical artifacts. Evidence is drawn from curricular artifacts, including a syllabus model, unit sequence, lesson prototypes specifications, and assessment tools. By situating the curriculum within the field’s pedagogical trajectory from current-traditional through multimodal pedagogies, the study shows how long-standing theories can be reorganized into a coherent curricular architecture when rhetorical agency and modality-use are explicitly named as the guiding threshold concept. Implementing dual pedagogy requires more than revised assignments. By naming and operationalizing the integration of rhetorical agency and modality-use, this dissertation offers FYC instructors a structured and transferable approach to teaching writing as both reflective practice and disciplined craft. The future of rhetoric and composition depends on acknowledging this persistent tension and designing curricula that cultivate rhetorical judgment and modal fluency as interdependent forms of knowledge.