Writing centers, an established, U.S.-rooted writing pedagogy, have spread across the globe, serving various populations in different countries. With Chinese universities' exciting endeavors to implement writing centers in their local contexts, little is known as to whether and how the writing center approach serves Chinese EFL students' specific needs. As a core medium of instruction of writing centers, the conferencing method, i.e., talking about writing during one-on-one tutorials, calls for more systematic, empirical research both in general and in the context of China. As such, with a hybrid methodology that combines discourse analytic and ethnographic techniques (Thonus, 1999, 2002) and by collecting both quantitative and qualitative data through survey, audio-recording, and interview, this study investigated whether and how Chinese college students' needs for English writing support were addressed in tutorials through talk in a writing center at a Chinese university. My findings revealed that writing centers offered an effective learning environment to address Chinese student writers' unmet needs for English writing support in depth via tutor-writer talk. In the unique dialogic space, tutors employed various tutoring strategies to teach (instruction), to push thinking (cognitive scaffolding), to motivate (motivational scaffolding) and to control the pace and direction of the tutorial (conference management); on the other hand, student writers used a myriad of interactive strategies to respond to tutors' tutoring moves and to self-scaffold learning, negotiate control, and establish rapport. In addition, tutor-writer talk not only enabled tutors and student writers to delve into complex writing issues such as synthesis writing, but also created a conducive environment for translanguaging practices and facilitated the transfer of writing knowledge. Drawing on Mackiewicz and Thompson's (2015) coding scheme for tutoring strategies and based on my fine-grained analysis of both tutor and tutee talk, I propose a Tutor-Writer Talk (TWT) Model to depict how tutors and writers co-construct talk about writing by orchestrating an array of tutoring and interactive strategies to achieve desirable learning outcomes. Teaching, tutoring, and research implications are offered to benefit university administrators, writing center directors, tutors, English writing instructors, and writing center researchers in the Chinese and EFL contexts. [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.]