Background/objectives: Several factors have been shown to play a role in the development and maintenance of generalized anxiety disorder (GAD), including intolerance of uncertainty and emotion dysregulation. Although the individual contribution of both of these factors is well documented, their combined effect has yet to be studied in a clinical population with GAD. The aim of the present study was to examine the relative contribution of intolerance of uncertainty and emotion dysregulation to the prediction of worry and GAD severity in adults with GAD. Methods: The sample consisted of 108 participants diagnosed with GAD. The participants completed measures of worry, GAD severity, depressive symptoms, intolerance of uncertainty, and emotion dysregulation. Results: Multiple regression indicated that both intolerance of uncertainty and emotion dysregulation significantly contributed to both worry and GAD severity, over and above the contribution of depressive symptoms. Of note, the model explained 36% of the variance in GAD severity scores. Conclusions: The present results provide preliminary evidence of complementarity among dominant models of GAD, and point to the potential role of integrative conceptualizations and treatment strategies for GAD.