Cross-sectional studies have shown that greater friendship satisfaction in adulthood is associated with many positive outcomes (Chopik, 2017; Gillespie, Frederick, et al., 2015). However, the developmental antecedents of satisfaction with close friends in adulthood have not been examined using prospective data. We do not know, for example, whether certain key experiences early in life, such as infant attachment security versus insecurity or the quality of maternal sensitivity, prospectively predict the degree of satisfaction with close friends in adulthood. We also do not know whether other salient experiences, such as the degree of peer competence in childhood or friendship security in adolescence, mediate relations between early life attachment and/or maternal sensitivity and adult friendship satisfaction. Leveraging data from the Minnesota Longitudinal Study of Risk and Adaption, we examined four developmental models containing these theoretically relevant antecedents of friendship satisfaction at age 32. The sample was approximately evenly split by gender (female = 82, male = 76), with the following ethnic distribution: White = 67.1%, Black = 8.9%, mixed race = 18.4%, other = 5.6%. All participants were born to mothers living below the poverty line at birth but on average were lower middle class by age 32. We found that the model containing direct paths from infant attachment security versus insecurity and from the quality of maternal sensitivity to friendship satisfaction at age 32 provided the best fit, suggesting that early parent--child relationships provide a foundation for later adult relationships with close friends. The implications of these findings are discussed.