Objective: Recent models suggest that generalized anxiety disorder (GAD) symptoms may be maintained by emotional processing avoidance and interpersonal problems. Method: This is the first randomized controlled trial to test directly whether cognitive-behavioral therapy (CBT) could be augmented with the addition of a module targeting interpersonal problems and emotional processing. Eighty-three primarily White participants (mean age = 37) with a principle diagnosis of GAD were recruited from the community. Participants were assigned randomly to CBT plus supportive listening (n = 40) or to CBT plus interpersonal and emotional processing therapy (n = 43) within a study using an additive design. Doctoral-level psychologists with full-time private practices treated participants in an outpatient clinic. Using blind assessors, participants were assessed at pretreatment, posttreatment, 6-month, 1-year, and 2-year follow-up with a composite of self-report and assessor-rated GAD symptom measures (the Penn State Worry Questionnaire; T. J. Meyer, M. L. Miller, R. L. Metzger, & T. D. Borkovec, 1990; Hamilton Anxiety Rating Scale; M. Hamilton, 1959; assessor severity rating; State-Trait Anxiety Inventory-Trait Version; C. D. Spielberger, R. L. Gorsuch, R. Lushene, P. R. Vagg, & G. A. Jacobs, 1983) as well as with indices of clinically significant change. Results: Mixed models analysis of all randomized participants showed very large within-treatment effect sizes for both treatments (CI = [-0.40, -0.28], d = 1.86) with no significant differences at post (CI = [-0.09, 0.07], d = 0.07) or 2-year follow-up (CI = [-0.01, 0.01]), d = 0.12). There was also no statistical difference between compared treatments on clinically significant change based on chi-square analysis. Conclusions: Interpersonal and emotional processing techniques may not augment CBT for all GAD participants. Trial Registry name: Clinical Trials.gov, Identifier: NCT00951652. (Contains 4 footnotes, 3 tables, and 1 figure.)