This study examined the interrelationships among mattering to friends, self-esteem, spirituality, and perpetration of relational aggression in friendships among 457 college students. While the three self-belief variables were positively related to each other, only spirituality and mattering to friends discriminated between men and women. Women reported higher spirituality and mattering to friends, and men reported slightly higher self-esteem. Perpetration of relational aggression was negatively related to mattering to friends and self-esteem and was not related to spirituality. Findings are discussed in light of Erikson's theory of adolescent development and Gilligan's theory of interpersonal relationships.