The best means for the diagnosis and treatment of reactive attachment disorder of infancy and early childhood have not been established. Though some longitudinal data on institutionalized children is available, reports of maltreated young children who are followed over time and assessed with measures of attachment are lacking. This paper presents the clinical course of a set of maltreated fraternal twins who were assessed and treated from 19 months to 30 months of age and then seen in follow-up at 3 and 8 years of age. A summary of the early assessment and course is provided and findings from follow-up assessments of the cognitive, behavioral, and interpersonal functioning of each child is analysed. Follow-up measures, chosen to capture social-cognitive processing of these children from an attachment perspective, are highlighted. Finally, findings from the case are discussed from nosological and theoretical perspectives.