The present study explores the transmission of attachment and family functioning across three generations. It is based on a sample of 460 female emerging adults (aged 18–26), their mothers (N = 440), fathers (N = 368), maternal grandmothers (N = 224), and maternal grandfathers (N = 113). Participants self-assessed their attachment anxiety and avoidance using the Relationship Style Questionnaire and evaluated the functioning of their families of origin using the Family Adaptation and Cohesion Scale–IV. The results reveal two mechanisms, both of which have a small but significant effect on the development of attachment across generations. The first operates via direct trans-generational transmission of attachment from parent to child, mainly involving the mother–child dyad, while the second operates through primary family functioning, especially balanced family cohesion, but also enmeshment and chaos in the case of attachment avoidance. The findings highlight the importance of including content related to attachment and family functioning in intervention programs.