Lesbians report experiencing intimate partner violence (IPV) at rates greater than or equal to those reported by heterosexual women. However, relatively little is known about the underlying mechanisms contributing to IPV perpetration among lesbians. In the present study we tested a conceptual model of the relationship among general life stressors, sexual minority stressors, negative affect, hazardous alcohol use, interpersonal intrusiveness (i.e., possessiveness/jealousy, separation anxiety, emotional interreactivity), and physical assault perpetration. We hypothesized that stressors would be more distal factors associated with increased negative affect and alcohol use which would in turn be associated with more interpersonal intrusiveness and physical assault perpetration. Self-identified lesbian women (N = 342) completed an online survey assessing life stress, sexual minority stress, negative affect, hazardous alcohol use, intrusiveness, and perpetration of physical assault. Results of structural equation modeling revealed negative affect and intrusiveness sequentially mediated the relationship between both minority and general life stress and physical assault perpetration. Also, life stress was related to increased hazardous alcohol use which was then associated with physical assault perpetration. Our conceptual model linking stressors to physical assault perpetration was mostly confirmed among this sample of lesbians. The results offer important information relevant to policies and clinical interventions aimed at reducing IPV in lesbian couples.