Obsessive-compulsive personality disorder (OCPD) remains understudied despite its high community prevalence and substantial societal burden. Elucidating the factors involved in OCPD traits and behaviors could improve conceptual models of OCPD and guide treatment development. Intolerance of uncertainty (IU) has been investigated as a transdiagnostic factor linked to many conditions, including anxiety disorders and obsessive-compulsive disorder (OCD). Despite OCPD's links to OCD, very little research has investigated whether IU may also be a relevant factor in OCPD. The present study administered measures of IU and OCPD to a large community sample of adults (n = 534) as well as a group of individuals with self-identified OCPD (n = 76). The OCPD measure assessed five OCPD trait dimensions as well as overall OCPD severity. We also included measures of other symptoms (OCD, depression, anxiety, and stress) as well as quality of life. Results revealed that the OCPD group reported heightened IU compared with the community sample, even when controlling for group differences in anxiety, depression, stress, and OCD symptoms. IU was significantly correlated with OCPD trait severity, and regression analyses demonstrated that IU predicted severity of OCPD traits controlling for distress symptoms. Moreover, IU significantly mediated the relationship between OCPD traits and reduced quality of life. These results highlight the importance of considering IU in the context of OCPD, with possible implications for improving treatment. Limitations and future directions for research are discussed. (PsycInfo Database Record (c) 2020 APA, all rights reserved).