Children with oppositional defiant disorder (ODD) can have heterogeneous presentations due to varying combinations of the eight criterion A symptoms. Researchers have identified a subtype of ODD for children with primarily angry/irritable mood symptoms and who are at risk for developing mood and anxiety disorders. Despite the prevalence of anger and mood issues in children with ODD, established treatments for disruptive behavior disorders typically focus primarily on teaching caregivers more effective parenting strategies to address oppositional and defiant behaviors, rather than directly targeting children's difficulties with emotions. To address the dearth of emotion-focused treatments for ODD, a novel emotion regulation intervention was developed based on a framework offered by Southam-Gerow (2013). The purpose of the current study was to evaluate the initial feasibility of this intervention and to explore its efficacy for reducing ODD and associated emotion regulation problems in middle childhood. Following a non-concurrent multiple baseline design, children ages 8-12 were assessed with semi-structured diagnostic interviews to determine study eligibility, and subsequently enrolled in a 13-week intervention with their caregivers. Treatment feasibility was supported by participant satisfaction ratings as well as treatment fidelity results. Treatment protocol adherence in terms of delivery by the therapist was high, but caregiver symptom reporting was less consistent. Nevertheless, multiple metrics support the efficacy of the intervention in reducing symptoms of ODD as well as some efficacy in improving child emotion regulation abilities. Overall, results support further research into emotion regulation-focused intervention for ODD.