The measurement of perfectionistic cognitions has recently caused disagreement among researchers. Flett, Hewitt, Blankstein, and Gray proposed that perfectionistic cognitions are unidimensional. However, after re-examining the factor structure of the instrument used to measure perfectionistic automatic thoughts (Perfectionism Cognitions Inventory [PCI]), Stoeber, Kobori, and Tanno argued that perfectionistic cognitions are multidimensional. Researchers are now faced with a dilemma: Should they adopt a multidimensional approach derived from the analysis of the underpinning structure of the instrument or should theory take precedence and the instrument be revised? In considering these two alternatives, in this instance, we advocate the latter strategy. In accord, in the current study, we assess the factor structure of the PCI with the intention of creating a unidimensional version of the instrument. In doing so, we provide evidence to support the use of a new shorter version of the PCI. Unlike the original PCI, the Perfectionism Cognitions Inventory–10 (PCI-10) has a unidimensional structure that replicates across independent samples. The PCI-10 and the original PCI are also highly correlated. Based on this evidence, we propose that the PCI-10 provides a short, psychometrically sound, instrument to measure perfectionistic cognitions in the unidimensional manner it was intended.