Pediatric obsessive-compulsive disorder (OCD) is associated with emotion regulation (ER) difficulties. Most studies are based on self-reports, while few have examined how these difficulties are expressed across modalities, which may hold important diagnostic and therapeutic information. We applied a multi-informant and multi-method approach to examine ER difficulties in 211 children aged 8-17 years: 121 with OCD and 90 non-clinical controls. Child ER difficulties were assessed with The Difficulties in Emotion Regulation Scale (self-report and parent-report) and a Tangram frustration task with investigator-rated behavior, self-rated frustration, and heart rate variability (HRV). Children with OCD differed significantly from non-clinical controls in showing: (i) elevated child ER difficulties on self-report (partial eta squared =.068-.165) and parent-report (partial eta squared =.207-.369); (ii) more investigator-rated ER difficulties during the task (Cohen's d = -.33); (iii) increased levels of self-rated frustration before and after the task (partial eta squared =.089); notably, the magnitude of this increase did not differ between children with and without OCD. Finally, (iv) all children, regardless of group, demonstrated significant HRV changes during the frustration task, with no discernible group differences in the magnitude of these changes. Results suggest the OCD-related experience of ER difficulties may not impact autonomic functioning.