ObjectivesInterpersonal emotion regulation (ER) plays a significant role in how individuals meet others' emotional needs and shape social interactions, as it is key to initiating and maintaining high-quality social relationships. Given that individuals with borderline personality disorder (BPD) or Asperger's syndrome (AS) exhibit problems in social interactions, the aim of this study was to examine their use of different interpersonal ER strategies compared to normative control participants. MethodsThirty individuals with AS, 30 with BPD, and 60 age-, gender-, and education-matched control participants completed a battery of measures to assess interpersonal ER, which assessed to what extent participants tended to engage in interpersonal affect improvement and worsening and to what extent they used different strategies. Before completing those measures, all groups were screened for disorders of Axis I and Axis II with the Structured Clinical Interview for DSM-IV Axis I and Axis II Disorders. ResultsCompared to controls, individuals with AS and with BPD engaged less in affect improvement. No differences were found for affect worsening. Individuals with AS reported to use less adaptive (attention deployment, cognitive change) and more maladaptive (expressive suppression) interpersonal ER strategies, compared to individuals with BPD and control participants who did not differ from each other. ConclusionsThe obtained results suggest the need to develop tailored ER interventions for each of the clinical groups studied. Furthermore, they highlight the need to study further potential differences in intrapersonal and interpersonal ER in clinical populations. Practitioner points Individuals with Asperger's syndrome (AS) and borderline personality disorder (BPD) engaged significantly less than healthy controls in interpersonal affect improvement. Individuals with BPD did not differ from healthy controls in the use of interpersonal strategies. Individuals with AS reported to use more maladaptive and less adaptive strategies than BPD individuals and healthy controls. Understanding differences in interpersonal emotion regulation in individuals with AS and with BPD and normative controls might help practitioners develop better interventions.