A meta-analysis was conducted to determine whether differences in efficacy exist among treatment approaches applied to youth. Included were all studies published between 1980 and 2005 involving participants 18 years of age or younger with diagnoses of depression, anxiety, conduct disorder, and attention-deficit/hyperactivity disorder that contained direct comparisons among two or more treatment methods intended to be therapeutic. Effect sizes were found to vary significantly, providing some evidence that differences in efficacy exist among treatments for these disorders in youth. However, the upper bound of the true difference in effects among treatments was small. Furthermore, researcher allegiance was found to be strongly associated with the difference in effect sizes so that when allegiance was controlled there was no evidence of any differences among treatments.