Grounded in interpersonal acceptance–rejection theory, this study examined the relation between recollections of parental rejection during childhood and fear of intimacy (FOI) in adulthood, as mediated by adults’ psychological maladjustment. In Study 1, the Fear of Intimacy Scale (FIS) was adapted for use in Italy. Its psychometric properties were investigated in a sample of 635 adults (51% women; 18–35 years). Confirmatory factor analysis, reliability analysis, and measurement invariance analysis showed that the Italian version of the FIS is a valid, reliable, and gender invariant scale. In Study 2, the relations among adults’ recollections of maternal and paternal rejection in childhood, current psychological maladjustment, and self-reported general FOI were investigated in a sample of 360 Italian adults (51% women; 18–35 years). Path analysis showed that the association between recollections of parental rejection during childhood and FOI in adulthood is fully mediated by psychological maladjustment, particularly emotional unresponsiveness, negative self-esteem, and dependency. This model was not moderated by gender. These results provide useful indications for the design of interventions aimed at reducing FOI.