Minimal information about the relationship between anxiety disorders and externalizing disorders in youth is available. This study examined relationships between different specific anxiety and externalizing disorders and examined whether these associations varied by age and gender. The Methods for the Epidemiology of Child and Adolescent Mental Disorders (MECA) data set, consisting of youth from ages 9 to 17 recruited at four sites across the United States using a probability sampling method, was used. Results indicated that all externalizing disorders (attention-deficit hyperactivity disorder, oppositional defiant disorder, and conduct disorder) were positively related to a range of anxiety disorders. The magnitude of these associations tended to be stronger for males than for females (particularly for associations between social phobia and all externalizing disorders) and at younger, compared to older, ages (particularly for the association between oppositional defiant disorder and overanxious disorder). The cross-sectional positive relationships between externalizing and anxiety disorders vary somewhat based on gender, age, and which specific pair of disorders is examined; this may help explain the discrepant findings of previous research in this area.