Debate has ensued regarding the appropriate assessment and diagnosis for school-age children who display severe behavioral problems as a result of previous abuse and neglect within the primary attachment relationship. The current nomenclature recognizes reactive attachment disorder and some clinicians have suggested broader categories of attachment disorder. These attempts at classification are often criticized on empirical grounds; however, often lost in these criticisms is the fact that that these diagnostic approaches often misapply attachment theory and research. This article summarizes the original contributions of John Bowlby and other attachment researchers to our understanding of child development, examines misguided attempts to apply attachment theory to the diagnosis and assessment of maltreated children, and offers a diagnostic conceptualization and assessment recommendations consistent with the available attachment research.