We examined how men in treatment for intimate partner violence and non-violent men described the mother of their child, and their co-parenting. We interviewed six cohabiting and five non-cohabiting fathers in treatment for intimate partner violence (IPV), and six non-violent fathers on their everyday-life experience of being a father. We performed a theory driven thematic analysis, using ‘we-ness’ as an organising concept. In contrast to non-violent fathers, partner-violent fathers’ descriptions of the co-parenting relationship lacked reference to mutuality, respect and an understanding of family dynamics. Partner-violent fathers tended to present the child’s mother negatively, with non-cohabiting fathers using more categorically negative characteristics. Men in IPV treatment also described more undermining co-parenting behaviours. Therapeutic interventions for men who have used IPV should focus on developing basic perspective-taking skills towards their (ex-)partner and child. With men who are cohabiting, couple sessions on co-parenting should be considered. In separated couples, this work may be more safely conducted individually. The effects of IPV on co-parenting, and through co-parenting on child development, should routinely be explored in therapy.<br/><br/>Key messages<br/><ul><li>Men who have used IPV exhibit little reciprocity and understanding of family dynamics, and how these may affect children’s development.</li><br/><li>Interventions for partner-violent men who have contact with their children should include a focus on parenting and co-parenting, building basic co-parenting skills.</li><br/></ul>