This thesis investigates the potential role of Wegner’s (1994) theory of ironic processes of mental control in a performance context. Chapter 1 reviewed the literature on Wegner’s (1994) theory in a performance setting. Chapter 2 addressed a significant limitation of previous ironic effects research by differentiating ironic performance errors from non-ironic performance errors. Specifically, when instructed not to miss in a specific direction, anxious performers did so a significantly greater number of times; importantly, there was no difference in non-ironic performance error, which provides the first specific support for this prediction of Wegner’s theory in a performance context. Chapter 2 also presents the first examination of the precision of ironic errors. When anxious, participants performed not only more ironically but also performed more precisely in the to-be-avoided zone than when they were not anxious. Chapter 3 reports the first examination of neuroticism as a predictor of the incidence of ironic processes of mental control. Moderation analyses revealed a consistent moderating effect of neuroticism on the incidence of ironic errors under pressure. Specifically, when anxious, neurotics displayed prominent increases in ironic performance error, and more dramatic decreases in target performance. Chapter 4 present three novel tests of Wegner’s (1994) theory in an externally paced task under conditions of low-and high-anxiety. To our knowledge, this is the first evidence that participants made significantly more ironic errors when anxious during reactive motor tasks (Study 5 and 6). Results from Study 7 provide the first evidence that instructional interventions can reduce the incidence of anxiety-induced ironic performance errors in reactive motor tasks. The performance of movement is more successful when (self-) instructions pertain to what to do as opposed to what to avoid. The last chapter (Chapter 5) discusses the findings emanating from this thesis in relation to the theory of ironic processes of mental control (Wegner, 1994) and the anxiety-performance relationship more globally.