Intolerance of uncertainty (IU), which can include prospective (i.e., desire for predictability) and inhibitory (i.e., uncertainty paralysis) IU, is widely understood to be a central underlying component of obsessive-compulsive disorder (OCD).  IU has several treatment implications, yet research on the differences in IU underlying OCD dimensions is limited and does not account for covarying effects of overlapping symptoms, shared variance in IU, demographic variables, and comorbid psychiatric conditions like generalized anxiety disorder (GAD) and posttraumatic stress disorder (PTSD).  A sample of 974 patients with diagnosed OCD enrolled in residential, partial hospitalization, and intensive outpatient treatment programs for OCD and anxiety completed self-report measures of OCD symptoms and IU at admission.  Structural equation modeling included prospective. inhibitory IU, and common IU and covariates (i.e., race, ethnicity, level of care, and comorbid GAD and PTSD) as predictors of four common OCD dimensions found that contamination and unacceptable thoughts symptoms evidenced a unique relationship with IU.  Specifically, whereas a common IU factor predicted all four OCD symptom dimensions, inhibitory IU uniquely predicted contamination and unacceptable thoughts symptoms over and above covarying effects.  Individuals with contamination and unacceptable thoughts symptoms may be more likely to feel “paralyzed” by uncertainty due to overreliance on overt immediate rituals, outright avoidance, rumination, or difficulties with emotion regulation, and may benefit from additional psychoeducation, problem-solving, and accountability.  Conversely, individuals with responsibility and incompleteness symptoms may be more likely to engage in complex and cognitively taxing rituals to obtain certainty and may benefit from explicit discussions about expectancies and disconfirmation of fears.