Indiana University-Purdue University Indianapolis (IUPUI) / This thesis explores the developmental pathway of thematic coherence among one Saudi female student in a foundational second language (L2) writing composition course, contributing to the field of L2 academic writing by offering a rich description of writing development. Despite a rapid increase in enrollment in the past 10 years, students from the Kingdom of Saudi Arabia (KSA) remain an understudied L2 learner population. In addition, although a number of studies have explored coherence among L2 learners of English, such research focuses either on the linguistic features utilized by learners to ensure cohesion or on the contrast between L2 learners’ cohesive devices and that of professional standards. To date, no studies offer insight into learners’ developmental trajectory toward greater competency in producing coherent academic paragraphs. The present study proposes an alternative approach by analyzing academic paragraphs in light of the definition of thematic coherence as a general-to-particular structure of ideas, i.e., a flow of information to form a superordinate-subordinate structure in which subordinate ideas support the abstract, overarching assertion. Further, the study uses the methodology of a microgenetic analysis to facilitate the tracing of the history of mediation and micro-changes in the focal learner’s written production over time as it relates to the proposed definition of thematic coherence. Each of the written drafts of paragraphs produced by the focal student is analyzed in sequence. An analysis of qualitative data is presented to contextualize and describe the focal learner’s experience in the instructional context and how this is interconnected to the development of her written paragraphs. The results showed an increase in the student’s ability to produce academic paragraphs with a general-to-particular structure, particularly during mediation that was rich with metalinguistic terminology that also created opportunities to collaboratively construct meanings of such terms. A main contribution to L2 academic writing this study offers is a rich description of a student’s developing skills in producing academic paragraphs. An implication is that to nurture academic writing skills, such as thematic coherence among students from KSA, instruction must be attentive to the developmental stages this student population progresses through.