Distress tolerance has fuzzy boundaries with neighboring emotion regulation abilities. In the present study, we probed the structure of this domain and examined its link to emotional disorder outcomes. We recruited mental health patient (ns = 225 and 210) and university student (n = 1,525) samples to report on diverse components of distress tolerance, emotion dysregulation, experiential avoidance, and anxiety sensitivity. Confirmatory factor analysis supported a one-factor model of these individual differences; this broad dimension was closely related to depressive symptoms (standardized effect range =.63 to.74) and suicide risk (.42 to.50), and it was almost perfectly associated with a latent dimension representing borderline personality disorder features (.93-.97). We conclude that a reformulation of this domain—with special attention to discriminant validity—would help understand how distress tolerance is so intimately intertwined with emotional health. The data sets and analysis code for this study are published at https://osf.io/8ab2v/.