The Purpose of this dissertation is to explore undergraduate Computer Science (CS) students' writing processes and transfer as they occur in the process of completing a writing assignment in a CS course. In particular, I observe and analyze students' writing processes, and investigate examples of writing knowledge transfer from prior and concurrent writing contexts such as First-Year Composition (FYC) courses and extracurricular activities. To explore my participants' writing process and transfer, I use Beaufort's (2007) writing expertise model of five knowledge domains: discourse community knowledge, subject-matter knowledge, writing process knowledge, rhetorical knowledge, and genre knowledge. In addition to conducting two interviews with each participant, I draw upon Driscoll's (2022) novel methodology of using Google Documents and Google Draftback to analyze participants' writing assignments. My findings revealed that students had different strategies for writing their way into professional engagement in CS, which influenced their writing processes and transfer. Participants in this dissertation were divided into two groups, field-wide enthusiastic students (FWE) and coursework-focused students (CWF). FEW students expressed engagement in extracurricular activities through which they gained transferrable writing knowledge and skills. CWF students concentrated on coursework requirements where they gained professional and writing skills. I found that these nuances of students' experiences influenced how they wrote their assignments and how they transferred knowledge from prior and concurrent writing situations. They also influenced students' writerly identities and confidence in perceiving themselves as writers and in performing writing tasks. In chapter four, I present findings as per students' writing backgrounds and writerly identities, their engagement in Beaufort's (2007) knowledge domains, and an analysis of their writing assignments, drawing heavily from Draftback-generated analytics. I summarize my findings in five themes that feature students' professional engagement and writerly identities, writing-to-learn opportunities, transfer of prior knowledge, transfer of concurrent knowledge, and discourse community practices. The term discourse community practice is what I suggest as an expansion of Beaufort's (2007) domain of discourse community knowledge. In chapter five, I thoroughly discuss these findings and present implications for CS and STEM programs, writing across the curriculum (WAC) and writing in the disciplines (WID) programs, and FYC. I end my implications with suggestions for future research. This dissertation contributes important findings to the scholarship of CS writing and the broader STEM writing research in several ways. First, I provide a potential categorization of CS students, FWE and CWF, which can benefit STEM programs in raising awareness of students' nuanced needs. I explain how extracurricular activities promote students' concurrent writing transfer experiences. I expand Beaufort's (2007) domain of discourse community knowledge to include discourse community practice, which co-constructs students' writerly identities. I present a framework for writing to learn assignments to benefit STEM as well as WAC/WID programs in integrating writing into the curriculum. I also discuss how FYC can work as an entry point into students' disciplinary engagement. Such contributions build the writing studies field towards stronger writing support for students across the disciplines. [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.]