Although previous research has suggested cortisol-emotion relationships, little is known regarding the effect of anxiety type on cortisol levels or relationships between anxiety and longitudinal cortisol change in adolescents. The authors examine the differential relationship of cortisol levels with generalized and social anxiety and relationships between longitudinal cortisol change and anxiety in 106 youth ages 9 through 14. Cortisol levels were assessed three times at 6-month intervals; anxiety sections of the Diagnostic Interview Schedule for Children were administered at the final occasion of measurement. In girls, cortisol exhibited positive relationships with concurrent general and social anxiety. Greater cortisol increase across the year predicted higher general and social anxiety in girls at the end of the study. No significant relationships were found in boys. Sex differences may reflect differences in the physiology of anxiety or in self-reports of emotion. (Contains 4 tables and 1 figure.)