This study assesses the influence of writing center tutorials on student writing and presents tutoring best practices. Writing center scholars have emphasized the need for evidence-based studies to understand how one-on-one tutorials influence student writing practices. After examining twenty tutorial recordings along with their pre-and post-intervention drafts in two state universities (ten in each university), the author traced the influence of writing center tutorials on students' post-session revisions and identified tutoring best practices. The findings show that all the twenty students included in the study followed up on the issues addressed in their tutorials, in some form or the other, in their post-session drafts. In terms of tutoring strategies, the findings revealed that although most of the tutors in the study could identify and speak about global concerns (i.e. development, structure, purpose, audience), many lacked specific strategies to address these concerns effectively. To address this concern, this study identifies tutoring best practices related to global concerns. Furthermore, the findings also revealed that the tutors faced challenges navigating the directive/non-directive continuum of tutoring. To address this concern, this study presents tutoring best practices to demonstrate how tutors can shift flexible between directive and non-directive strategies during a session. / Ph. D.