This paper presents the relationship between perfectionism and intolerance of uncertainty with psychopathological variables. This study has a triple aim: firstly, to determine the psychometric properties of a 26-item version of Frost’s Multidimensional Scale of Perfectionism; secondly, to verify the dual model of perfectionism; and thirdly, to examine the transdiagnostic process of perfectionism. For this purpose, we used a sample 427 people, which had 64.1% women, 62.0% had higher studies, and the average age was 26.8 years (DT=10.6). The results confirm the dual-process model of perfectionism with regard to the trait of worry. With regard to the transdiagnostic process, it is suggested to be a common process shared by the psychopathological variables, uncertainty that generates inhibition. The results are discussed taking into account the dual-process model of perfectionism, and the model of avoidance of worry and the generalized anxiety disorder, as both are supported by Mowrer’s (1947) bifactor theory.