The current studies examined whether several risk and protective factors operate similarly for intimate partner violence (IPV) and same‐sex aggression (SSA) in the same sample, and to assess whether they show similar associations for men and women. Study 1 (N = 345) tested perceived benefits and costs, and instrumental and expressive beliefs about aggression: perceived costs predicted IPV and SSA for both men and women. Expressive beliefs predicted IPV (more strongly for women), and instrumental beliefs predicted SSA. Study 2 (N = 395) investigated self‐control, anxiety and empathy, finding that self‐control strongly predicted both types of aggression in both sexes. Study 3 (N = 364) found that primary psychopathy (involving lack of anxiety) was associated with IPV for men and SSA in both sexes, whereas secondary psychopathy (involving lack of self‐control) was associated with IPV and SSA in both sexes. Overall there were both similarities and differences in the risk factors associated with IPV and SSA, and for men and women. The implications of the findings for theoretical debates about the study of IPV are discussed. Aggr. Behav. 43:163–175, 2017. © 2016 Wiley Periodicals, Inc.