The purpose of this study was to investigate the relationships among transformational leadership, emotional complexity, and positive/negative emotions of leaders and followers. How leader openness, emotional complexity, gender, and trait affect may influence the extent to which leaders use various types of leadership and mentoring, and how all of these aspects may influence follower state affect and research self-efficacy were investigated. Participants included 493 faculty from Psychology departments throughout the United States, and 179 graduate students whom they supervised. Emotional complexity was positively related to faculty leaders' positive emotion but not negative emotion. No significant relationship was found between emotional complexity and transformational leadership. Emotional complexity moderated the relationship between faculty positive emotion and student positive emotion, and faculty positive affectivity (PA) and student negative emotion. When faculty emotional complexity was low, students experienced less positive emotion as faculty positive emotion decreased and more negative emotion as faculty PA decreased. Conversely, when faculty emotional complexity was high, faculty PA or positive emotions had little effects on students' emotion. No significant relationships were found between faculty PA and student positive emotion or faculty NA and student negative emotion, although faculty NA was found to be related to decreases in student positive emotion, and PA was found to be related to decreases in student negative emotion. Openness was found to be related to emotional complexity (both range and differentiation of emotion) and intensity of emotion. A strong positive relationship was found between faculty engagement in transformational leadership and students' experienced positive emotion in reference to their relationship with their faculty. Intellectual stimulation and individualized consideration were strongly related to students' positive emotion, and management by exception active and passive were related to students' negative emotion. Female faculty engaged in significantly more transformational leadership, psychosocial mentoring, and career-related mentoring than did male faculty. Faculty engagement in transformational leadership was strongly related to their engagement in both types of mentoring. Intellectual stimulation and individualized consideration were highly related to both types of mentoring. Both types of mentoring were positively related to student research self-efficacy Limitations, practical implications, and future research were discussed. [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/en-US/products/dissertations/individuals.shtml.]