Drawing on a multiple-case, embedded design (Yin, 2018), I highlight the in-depth differences and similarities that exist across students' experiences in first-year composition (FYC), looking specifically at whether learners used genre and rhetorical situation as threshold concepts to transfer writing-related knowledge and skills across the curriculum. I designed and conducted this research by drawing on theories of learning transfer (Perkins & Salomon, 1988; 1989; 1992; Salomon & Perkins, 1989), writing-related transfer (Moore, 2017; Nowacek, 2011; Yancey, Robertson, & Taczak, 2014; Yancey et al., 2019), and threshold concepts (Meyer & Land, 2006). Across this study, I collected data as I facilitated focus groups and interviews. In addition, I drew on course artifacts that student participants shared in order to better understand their perception of threshold concepts introduced in FYC, as well as to determine if this understanding supported them in negotiating writing invitations across the curriculum. Results showed that students seemed to draw on language, structure, and reference, concepts which were highlighted in their course text, more so than the threshold concepts, genre and rhetorical situation. Most participants possessed an awareness of disciplinary language conventions; however, when presented with the opportunity to apply specific language practices in disciplinary contexts, students returned to their frame of audience awareness--instructor as audience--rather than drawing on their disciplinary knowledge. Further, while students possessed at least some awareness of how reference varies across the disciplines, they often tied this awareness to a specific citation style that defined rules for what they were doing. Though participants did not consistently draw on genre and rhetorical situations as threshold concepts, one participant demonstrated the potential of this initiative. This study contributes to the conversation scholars in Writing Studies are having on writing-related transfer, teaching for transfer, and writing across the curriculum. Additionally, this dissertation highlights the need for recognizing and building on prior knowledge of both students and instructors, greater contextualization of disciplinary writing conventions in instruction, and a shared vocabulary and approach to teaching writing that builds bridges across the curriculum. [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://www.proquest.com/en-US/products/dissertations/individuals.shtml.]