Talk lies at the heart of writing center work, yet studies on tutorial interaction have predominantly focused on tutor talk while largely neglecting writer talk, especially at English as a Foreign Language (EFL) writing centers. To investigate tutorial interaction in a holistic manner, this study examined tutor-writer interaction during individualized writing tutorials at two university English writing centers in China—an EFL context where writing centers have garnered increasing scholarly attention yet scant empirical research. Based on recorded tutorials and retrospective interviews with faculty tutors and student writers, this study: 1) highlighted the co-constructed nature of tutorial interaction by expanding Mackiewicz and Thompson's (2015) spectrum of tutoring strategies and by proposing a systematic coding scheme for student writers’ interaction strategies, and 2) investigated tutors’ and student writers’ perceptions and evaluation of their tutorial interaction to offer context-specific implications on individualized writing support provision and tutorial interaction research in EFL contexts.