The present study explored the links between the quality of adolescents’ attachment to their mother and their father, separation anxiety and suicidal ideation. Self-report questionnaires were completed by French adolescents (n = 455; Mage = 15.78 years, SD = 1.61) to probe their attachment styles, separation anxiety (related to school phobia, a secure base, and family members), and suicidal ideation. Avoidantly attached adolescents displayed greater school phobia than securely attached adolescents. Female adolescents with an avoidant attachment to their father tended to report less fear related to family members than their secure counterparts. Male adolescents who were insecurely attached to their mother reported more separation anxiety than securely attached males. The structural models were significant for both boys and girls (R2 = .38 and .44, p < .001) with good fit indices. Mediation analyses revealed that separation anxiety partially mediated the negative effect of attachment to mother (especially alienation) on suicidal ideation for both girls and boys, and partially mediated the negative effect of attachment to father (especially alienation) on suicidal ideation for boys. These results support an individuated conception of attachment patterns, with a differential influence of dyadic relationships, and could provide a better understanding of adolescents’ suicidal ideation.