This paper reports on a decade of research into the nature of interactions between writing center tutors and native speaker (NS) and non-native speaker (NNS) tutees. It explores and describes the structure of this interaction and the behaviors of NNS tutees, and of tutors when interacting with both NS and NNS tutees. It characterizes writing center tutorials with NNSs as a balancing act among potentially conflicting forces. Finally, it suggests applications of these insights to tutor preparation and practice.