Affective organizational commitment is an important predictor of the willingness to contribute to organizational goals and is of particular relevance to family firms, as these firms often rely on long-term involvement of family members through transgenerational succession. Drawing on organizational commitment and ownership attachment theories, we probe the influence of family firm dynamics (i.e. family harmony and relationship conflict) on work-family conflict and family owner-managers' ownership attachment, which in turn impact affective organizational commitment. Based on a study of 326 family firms, we introduce ownership attachment as an important antecedent to affective organizational commitment. We find that ownership attachment is positively affected by both family harmony and work-family conflict, whereby work-family conflict is influenced by relationship conflict. We also find that work-family conflict affects ownership attachment.