Dialectical behavior therapy (DBT) has demonstrated effectiveness for a range of emotional difficulties, and DBT skills training groups may be necessary to produce symptom change. However, it is unclear how skills training groups influence outcomes. Specifically, is participation in DBT skills modules associated with general effects (i.e., changes in multiple domains) or domain-specific effects (i.e., changes in the conceptually relevant domain)? Participants recruited from a university training clinic ( n = 87; 75.9% diagnosed with borderline personality disorder) participated in standard DBT for 6 months. We conducted hierarchical linear mixed models to test whether self-reported changes in emotion regulation, interpersonal problems, and distress tolerance were associated with the specific DBT module intended to target that outcome. In 3 models, we regressed end-of-module ratings of each of our measures of interest on (a) premodule ratings of each measure of interest, (b) time, and (c) dummy-coded module completed. Although all modules were associated with similar reductions in emotion dysregulation, the Emotion Regulation module was associated with the greatest improvements in both interpersonal problems and distress tolerance. In contrast, the first skills module completed was unrelated to changes in any of these domains. These results suggest that Emotion Regulation skills are associated with improvements in patient symptoms across relevant domains and offer potential directions for optimizing the delivery of DBT. (PsycInfo Database Record (c) 2023 APA, all rights reserved).