This paper describes the assessment and treatment of children with peer relationship problems. The first part of the paper is organized around five topics: peer rejection, peer neglect, the absence of friendships, reputation in the peer group, and peer group affiliations. Next, a series of assessment methods is delineated, including peer, teacher, parent and self reports, as well as direct observational procedures. Finally, we suggest a number of treatment options, including social skills training, social cognitive interventions, and co-operative group interventions.