According to adult attachment theory (Hazan and Shaver, 1987), people's levels of insecure attachment, both anxious and avoidant, are associated with their abilities to regulate emotions in a relational context. This study is the first to test emotion dysregulation as a mediator for the relationships between levels of insecure attachment and psychological aggression using dyadic data. Cross-sectional, self-report data were collected from 110 couples presenting for couple or family therapy at an outpatient clinic. Data were analyzed using path analysis informed by the Actor-Partner Interdependence Mediational Model (APIMeM; Ledermann, Macho and Kenny, 2011). While the findings did not support a mediating role of emotion dysregulation between levels of anxious or avoidant attachment and psychological aggression, results indicated direct partner effects between people's own levels of anxious attachment and their partners' psychological aggression. Higher levels of anxious attachment were associated with higher levels of emotion dysregulation in both males and females; higher levels of avoidant attachment were only associated with higher levels of emotions dysregulation in females. Limitations and clinical implications for couple therapists are discussed.