Anxiety disorders are among the most common disorders affecting youths in the general population, with up to 10% of children and 20% of adolescents meeting criteria for an anxiety disorder at any one point in time. Cognitive-behavior therapies (CBT), varying between 9 and 18 weeks of treatment, are considered evidence-based for the treatment of anxiety disorders in youth. During the last two decades treatments that are brief, intensive, or concentrated (BIC) have been developed and this meta-analysis includes 23 RCTs of these new approaches across the anxiety disorders. BIC yielded a lower attrition (2.3%) than standard CBT (6.5%). The effect sizes (ES) for comparison of BIC with waiting-list (1.47) and placebo (0.91) were significant, whereas that with standard CBT (0.01) was not. Regarding remission at post/recovery at follow-up BIC (54%/64%) and standard CBT (57%/63%) were comparable and both were significantly higher than placebo (26%/35%), which was higher than WLC (7%/9%). Within-group ES at post and follow-up were 1.50 and 1.53 for BIC, and 0.98 and 1.05 for standard CBT, indicating maintenance of the effects up to 12 months after therapy. Advantages and disadvantages of BIC are discussed and we suggest that BIC-interventions represent a paradigm shift in the delivery of services for youth with anxiety disorders.