The purpose of this study was to examine cognitive biases in clinically anxious children compared to normal children and to determine if cognitive biases could discriminate anxious youth from non-anxious youth. Two specific cognitive biases were the focus of the present study—interpretive biases (i.e., the tendency to interpret neutral stimuli in a negative way) and judgment biases (i.e., a lowered estimate of one's ability to cope with a threatening situation). Twenty-four youth comprised the anxiety disordered sample and were each matched to two normal youth on four demographic variables (gender, age, ethnicity, and family income level), thus the matched comparison sample consisted of 48 youth (ages 7 to 17). Interpretive biases were assessed with the Children's Negative Cognitive Error Questionnaire (CNCEQ) and judgment biases were assessed with the Anxiety Control Questionnaire—child form (ACQ-C). In addition, self-reported symptoms of anxiety and depression and parent-reported internalizing and externalizing symptoms were measured. Results indicated that (1) children in the clinic sample exhibited significantly more interpretive biases and judgment biases relative to the control sample, and scored significantly higher on measures of anxiety, depression, and parent-reported internalizing and externalizing symptoms relative to the control sample, (2) the ACQ-C demonstrated incremental validity over the CNCEQ in predicting diagnostic status, (3) the ACQ-C predicted diagnostic status while controlling for Generalized Anxiety Disorder symptoms and parent-reported internalizing and externalizing symptoms, but not while controlling for RCMAS (anxiety) and CDI (depression) scores, and (4) the relationship between the CNCEQ and diagnostic status was moderated by age and gender. This study adds to the research literature by demonstrating elevated CNCEQ scores among youth with anxiety disorders compared to non-anxious youth and extends findings with the ACQ-C by showing its incremental validity beyond the CNCEQ. The results also add to the understanding of the assessment of negative cognitive vi errors by highlighting developmental and sex differences in their association with anxiety disorder status in youth. Implications of the positive findings for theory and practice are noted and theoretical and methodological reasons for the negative results are discussed to highlight suggestions for future work in this area.