Multivariate comorbidity research indicates mood and anxiety (internalizing) disorders share one or more common liabilities, but categorical, dimensional, and hybrid accounts of these liabilities have not been directly compared. We modeled seven internalizing disorders in a nationally representative sample of 43,093 individuals via confirmatory factor, latent class, exploratory factor mixture, and exploratory structural equation modeling analyses. A two-dimensional (distress-fear) liability structure fit best and replicated across gender, assessment waves, and lifetime/12-month diagnoses. These liabilities, not disorder-specific variation, predicted future internalizing pathology, suicide attempts, angina, and ulcer.