A longitudinal study of mentoring dyads was used to investigate the antecedents and consequences of liking in formal mentoring relationships. Demographic and deep-level similarity were examined as antecedents to liking in mentoring relationships. Following this, the association between the degree of liking and reports of mentoring functions provided was examined. Mentors and proteges differed in the similarity characteristics that impacted their perceptions of the mentoring relationship. Results also indicated that mentors' level of liking for proteges was not related to proteges' perceptions of mentoring functions received. Longitudinal data allowed examination of whether early perceptions of similarity predict final evaluations of mentoring functions. Analyses indicate that relationships change over time, further emphasizing the need to examine developmental relationships longitudinally.