<p>Children with attention-deficit/hyperactivity disorder (ADHD) often experience friendship difficulties, yet little is known about whether friendship quality differs according to the gender composition of their friendships. Drawing on developmental models of gendered friendship processes, we examined whether friendship quality differed across boy-boy, girl-girl, and mixed-gender dyads among children with ADHD. This secondary analysis used baseline data from a randomized clinical trial of children with ADHD aged 6 to 11 who were seeking treatment for peer problems. The sample included 149 children who brought a reciprocated friend to the baseline assessment: 87 boy-boy dyads, 44 girl-girl dyads, and 18 mixed-gender dyads. Friendship quality was assessed using multi-informant questionnaires and direct observations of dyadic interactions. Contrary to hypotheses, girl-girl dyads showed significantly higher observational positive friendship quality than boy-boy dyads, an effect that remained robust across sensitivity analyses. Questionnaire measures did not consistently differentiate boy-boy and girl-girl dyads, although sensitivity analyses among “close” and “best” friends suggested higher child-reported positive friendship quality in girl-girl dyads. Mixed-gender dyads generally did not differ from either same-gender group, but these contrasts were underpowered. Findings suggest that gendered friendship patterns among children with ADHD may more closely resemble those observed in neurotypical samples than expected. Results underscore the value of multi-method, multi-informant assessment and highlight the need for further research on friendships among girls with ADHD.</p>