Mentoring is a process by which a mentor, who usually is a more senior person, gives supports to a prot?g?, who usually is less in seniority. A mentor provides a prot?g? with eleven mentoring tasks, which can be categorized into three kinds of mentoring functions - (1) career related, (2) role model, and (3) psychosocial supports. Mentoring can be described, by the nature of relationship initiation, as informal and formal mentoring. While informal mentoring occurs spontaneously, formal mentoring needs a facilitator to match mentor-prot?g? pair and to encourage the relationship. This book studies the effect of personality fit on subjective success of mentoring. The study employs Myers-Briggs Type Indicator (MBTI) as an instrument to measure, and to compare the similarity of personalities. The findings of this study help those who involve with mentoring - whether being a mentor, a prot?g?, a facilitator, or a scholar - to effectively approach the mentoring process.