Research on mentorships has suffered from fragmentation of key issues; specifically, type of mentoring relationship, functions served by the mentor, and outcomes of the mentoring relationship. A field study was conducted comparing 212 proteges who were involved in informally developed mentorships, 53 proteges involved in formal mentorship programs, and 284 individuals who did not have mentors. Individuals in informal and formal mentorships were compared along two mentoring dimensions: psychosocial and career-related functions. All groups were compared on three outcome measures: organizational socialization, job satisfaction, and salary. Results indicated proteges in informal mentorships reported more career-related support from their mentors and higher salaries than proteges in formal mentorships. For all outcome variables, proteges in informal mentorships also reported more favorable outcomes than nonmentored individuals. However, outcomes from proteges in formal mentorships were generally not significant from the other two groups. Implications for mentorship practices and research are discussed.