Clinical Child and Family Psychology Review, Vol. 8, No. 2, June 2005 ( C  2005) DOI: 10.1007/s10567-005-4751-2 Anxiety Disorders in Childhood: Casting a Nomological Net Carl F. Weems 1,3 and Timothy R. Stickle 2 Empirical research highlights the need for improving the childhood anxiety disorder diagnos- tic classification system. In particular, inconsistencies in the stability estimates of childhood anxiety disorders and high rates of comorbidity call into the question the utility of the current DSM criteria. This paper makes a case for utilizing a nomological net 4 model for advancing the understanding of childhood anxiety disorders. In this article, we discuss measurement and assessment issues related to improving the childhood anxiety disorder diagnostic system and show how these issues can be addressed by employing the nomological net of childhood anxiety. Because employing the nomological net involves drawing from etiological process theories to facilitate classification and assessment, an integrative model of childhood anxiety disorders is presented as a tentative heuristic. Then evidence for the existing symptom sets is discussed in the context of how process theory mechanisms may be utilized to improve classifi- cation and assessment. Testable hypotheses are presented. Measurement, disorder definition, treatment, and policy implications are also discussed. KEY WORDS: childhood anxiety; comorbidity; treatment; diagnostic classification. Anxiety disorders are the most prevalent class of emotional disorders of childhood, can cause intense personal distress, and negatively impact children’s school and social functioning (Bernstein & Borchardt, 1991; Bernstein, Borchardt, & Perwien, 1996; Silverman & Ginsburg, 1998). The scientific understanding of childhood anxiety disorders is largely a function of the ability to reliably and validly identify, classify, and measure these phenomena. Major advances in understanding and treating child- hood anxiety disorders have resulted from utilizing the taxonomy provided by the Diagnostic and Sta- tistical Manual of Mental Disorders—Fourth Edition (DSM-IV; American Psychiatric Association, 1994). DSM-IV is a major accomplishment in scientific 1 Department of Psychology, University of New Orleans, New Orleans, Louisiana. 2 Department of Psychology, University of Vermont, Burlington, Vermont. 3 Address all correspondence to Carl F. Weems, Department of Psychology, University of New Orleans, New Orleans, Louisiana 70148; e-mail: cweems@uno.edu. 4 A nomological net can be briefly defined as the theoretical struc- ture of a construct. taxonomy. The current symptom lists that make up the diagnoses are the product of many individuals, years of research, current literature, and clinical experience (APA, 1994). However, researchers continue to question the validity of the childhood anxiety disorders (see Saavedra & Silverman, 2001). In this paper, we provide a model for revising and validating the childhood anxiety disorders diagnoses and for testing etiological theories of these disorders. The DSM-IV diagnoses of childhood disorders are primarily descriptive, emphasizing observed or reported symptoms rather than underlying causal mechanisms. As a result, the disorders are grouped primarily on the basis of shared symptoms. Emerging research indicates that developmentally and theoret- ically based assessment of anxiety disorder symptoms may provide a more sensitive assessment than the DSM-IV criteria in children (e.g., Scheeringa, Zeanah, Drell, & Larrieu, 1995; Scheeringa, Peebles, Cook, & Zeanah, 2001; Scheeringa, Zeanah, Myers, & Putnam, 2003). Saavedra and Silverman (2001) and Dadds, James, Barrett, and Verhulst (2004) have recently reviewed the taxonomy of childhood anxiety disorders and concluded that there is a need 107 1096-4037/05/0600-0107/0 C  2005 Springer Science+Business Media, Inc.