This grounded theory study explores the perceptions of 33 alumni of 10 Indonesian evangelical theological schools regarding the impact of informal mentoring, which they experienced during their time as students. Data from face-to-face interviews revealed that the informal mentoring relationships (a) helped them to handle their social and emotional needs especially in the first and second semester, (b) facilitated their spiritual growth, (c) helped them achieve their academic goals, and (d) helped them become aware of their potential and identify their ministerial calling and vocations. The findings of this study show that the impact of informal mentoring can be described as a "parental investment" on the part of the mentor into the life of the mentee that is affected by the context, takes place in a specific process, and is dependent on the qualities of the mentor. The context of this parental investment is characterized by the close proximity and interaction that mimics close family relationships, such as the residential dormitories with dorm father/mother, mealtime conversations, and counseling during new student orientation. The parental investment process is defined as social-emotional support, spiritual impact, academic support, and ministerial guidance. The qualities of the invested parent (mentor) include assuming parental roles, being good listeners, praying with the mentees, believing in them, and being spiritual and moral role models. Nonfaculty mentors were also influential during internships and ministry practicum. There was also a dark-side to the parental investment mentoring model. [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://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]