This paper assesses how a new materialist ontology can inform the sociological study of gender-related violence (GRV). The new materialisms are relational rather than essentialist; post-anthropocentric as opposed to humanist; and replace dualisms such as agency/structure, reason/emotion and micro/macro with a monist or ‘flat’ ontology. To make sense of GRV from within this ontology, we explore violence as assemblages of human and non-human matter and draw upon the DeleuzoGuattarian micropolitical concepts of ‘the war machine’ and ‘lines of flight’. While violence may supply a protagonist with new capacities (a line of flight), it typically closes down or constrains the capacities of one or more other parties in a violence-assemblage. This theoretical exploration establishes the basis for a methodological approach to studying GRV empirically, using a Deleuzian toolkit of affects, assemblages, capacities and micropolitics. The paper concludes with an assessment of what is gained from this new materialist ontology of GRV.