Over the past two decades sociology, including the sociology of family and personal life, has seen a ‘relational turn’ with a growing body of work seeking to explain the ‘social’ by taking social relations as the primary object of sociological analyses. Relational sociologies theorise relations in social terms as either inter-actions or trans-actions. Inter-actions are relations that bring separate entities together, while trans-actions posit a relation of interdependence between entities. This article introduces a third way of conceptualising relationality as intra-actions drawing on the posthumanist relational ontology proposed by feminist philosopher and physicist Karen Barad. Intra-actions are understood as social-natural or material-discursive relations of ontological inseparability and mutual constitution. Using illustrative examples from the author’s research, the article suggests that Barad’s relational ontology offers a fruitful and distinctive ontological underpinning for relational sociology and for relational approaches to theorising and studying family practices.