Antisocial disorders, such as oppositional defiant disorder (ODD) and conduct disorder (CD), are common reasons for youth to be seen for clinical intervention. The intent of this constructivist grounded theory study was to evaluate clinicians' perspectives on the aetiology of antisocial disorders. Six professionals from various professional backgrounds were interviewed in order to gain insight into how theoretical orientations influence the understanding of antisocial disorders and subsequent clinical approaches. The findings from the research interviews suggest a range of perspectives on aetiology, such as a variety of predisposing, precipitating, perpetuating and differentiating factors. The results illustrate relative consistency in the understanding of aetiology among practitioners from varying theoretical orientations. Further, a biopsychosocial approach to aetiology and clinical decision-making was emphasised, despite differing theoretical orientations.