Many graduate students (60%) do not complete their program of study. It is important for universities to find ways to increase student completion rate. The general problem is that online U.S. universities are faced with a high rate of PhD student drop out resulting in an increased number of students not being able to complete their doctoral studies. The purpose of this multiple linear regression study was to identify predictor variables of dissertation student stress and overall dissertation satisfaction. Deci and Ryan's self determination theory and Lazarus' theory of cognitive appraisal were used to guide this research to identify how student perception of mentor communication styles can be used to predict how students appraise stress and overall satisfaction with dissertation. A convenience sample of 178 dissertation students identified through several online dissertation student support and student-led Facebook groups completed the online survey. According to study results, student perception of questioning and preciseness as mentor communication styles predicted significantly lower scores of student appraisal of stress experienced in dissertation. However, student perception of verbal aggressiveness as a mentor communication style predicted significantly higher scores of student stress. Mentor behaviors of academic assistance, mentoring abilities, and personal connection predicted significantly higher levels of overall student dissertation satisfaction. Positive social change initiatives formed by faculty and staff can be made to educate dissertation chairpersons about the communication style and behaviors that are the most effective in mentoring dissertation students.