Background: Generalized Anxiety Disorder (GAD) in youth is characterized by excessive worry across domains for ≥6 months, an inability to stop worrying, and at least one physiological symptom. This study examined the multiple domains that optimally distinguish (1) GAD youth from nonanxiety-disordered youth and (2) GAD youth from other anxiety-disordered youth. Methods: Receiver operating characteristic analyses examined a sample of youth (N=180) aged 7–13 (M=10.10; 52% male), to determine optimal cut scores to distinguish GAD youth from (1) nonanxiety-disordered youth and (2) other anxiety-disordered youth. The diagnostic efficiency of worries and physiological symptoms was also examined. Results: By parent report, three worries and four physiological symptoms had favorable cut scores, and several specific worries possessed high diagnostic efficiency. Children endorsed fewer GAD symptoms. Conclusions: Recommendations are made regarding the criteria for GAD in youth and interview sequencing of symptom queries. Depression and Anxiety 0:1–10, 2010.© 2010 Wiley-Liss, Inc.