The present study examined the impact of alliance ruptures (AR) on outcome expectations among 38 individuals who received cognitive-behavioral therapy for generalized anxiety disorder. ARs had a significant adverse impact on immediate post-rupture outcome expectations compared to dyads experiencing no AR. ARs also had a far greater negative impact on outcome expectations among those who were initially skeptical about treatment. Finally, path analysis indicated that the impact of an AR on posttreatment outcome was mediated by its influence on outcome expectations. These findings suggest an important role for preventing and repairing ARs, particularly among those who initially have doubts about treatment benefit.