<p dir="ltr">Overcontrol is a coping style common to many psychiatric disorders that involves rigidity, goal persistence, and relying on a strict set of beliefs to manage aversive experiences. Overcontrol is associated with many core deficits, including disorders of internalizing and difficulties with social function. In clinical observation, it has been noted that there are two subgroups of patients with overcontrol, those who are “overly agreeable” and “overly disagreeable”. This work aimed to examine the role of agreeableness in overcontrol, investigating whether there exist important differences in psychiatric or psychosocial functioning at the poles of agreeableness. This study found evidence of this non-linear relationship for certain outcomes. For example, the relationship between internalizing distress and emotion dysregulation was non-linear in nature, meaning particularly low/high agreeableness in combination with overcontrol predicted more depression and dysregulation. Further nuance to these findings were investigated in exploratory analyses. Contrary to expectations, there was no evidence for a curvilinear role of agreeableness in social functioning, however, overcontrol was significantly related to loneliness. Further, there were many associations between agreeableness, overcontrol and interpersonal values, lending credence to clinical observation that people high in overcontrol hold certain values about their interpersonal context which may not be overtly expressed. Taken together, this paper offers support for the Radically Open Dialectical Behavioral Therapy conceptualization of behavior, providing empirical support to the agreeableness subgrouping.</p>