In this chapter, we review the research on peer relationships of children and adolescents with attention-deficit/hyperactivity disorder (ADHD). We discuss potential explanations for peer relationship problems in this population and describe research on psychosocial interventions to address these problems. Many children and adolescents with ADHD have difficulties with peer relationships. Relative to their neurotypical peers, they are less liked and more disliked by classmates, are at higher risk of being socially neglected, have fewer dyadic friendships, and are at risk of being victims and/or perpetrators of bullying. These peer relationship difficulties are predicted by the negative social behaviors associated with ADHD symptoms that are inherently socially disruptive, symptoms of co-occurring disorders, and by relatively low levels of positive social behaviors. For the most part, research suggests that the social behavioral difficulties of youth with ADHD are due to performance deficits. However, it is equally important to consider peer group attitudes and social dynamics as factors affecting peer relationships of youth with ADHD. Peer relationship problems are important to address because these difficulties in childhood predict adverse outcomes in adolescence and emerging adulthood. Clinic-based interventions such as social skills training are typically ineffective. Interventions that involve parents and teachers as well as youth with ADHD, however, have an impact on ADHD symptoms, externalizing behaviors, and social impairment. Nevertheless, likely due to reputational bias, the interventions that have rigorous research designs have not been associated with changes in peer status.