This qualitative study explored how student writers adjust to the shifting composing demands in a multitude of composing contexts: in English, in history and across the two disciplines, as well as in various modes, including alphabetically and multimodally. Naturalistic inquiry case study was applied to explore the participant's experiences with these shifting composing contexts by addressing the following questions: (a) How does a student's perception of composing differ across disciplinary contexts, such as in a history class rather than an English class? How does this change when the composing is done in a cross-curricular project that spans both history and ELA? (b) Because new literacies expand the choices students must make through multimodal composing, what relationship can be seen between the authoring choices a student makes while composing multimodally and the literacy demands of various content area classrooms? (c) How does a student who is engaging in cross-curricular inquiry in both English and history perceive the disciplinary demands specific to each content area? (d) How do teachers account for the negotiation students must undergo in order to meet both English and history curricular goals in that cross-curricular project? Findings suggest that student agency and choice are important factors in helping students address shifting contexts for composing. These factors seem to alleviate the sense of anxiety and ambiguity students perceive when faced with shifting and unfamiliar composing demands. Importantly, multimodal composing supported writer's agency by offering vast choices and allowing students to use composing in support of inquiry. [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.bibliotheek.ehb.be/en-US/products/dissertations/individuals.shtml.]