Major depressive disorder (MDD) and borderline personality disorder (BPD) are characterized by disturbed patterns of emotional and interpersonal functioning, which might imply altered use of emotion regulation in interpersonal contexts. In the current study, we examined how individuals with MDD and/or BPD differ from healthy controls in (1) their overall daily life use of expressive suppression and social sharing and (2) their tendency to adjust the use of these strategies to the emotional context (i.e., preceding negative and positive affect). Thirty-four individuals with MDD, 20 individuals with BPD, 19 individuals with comorbid MDD and BPD, and 40 healthy controls participated in a week of experience sampling during which they reported their use of expressive suppression, social sharing, and experienced negative and positive affect. The results indicated that all clinical groups reported more expressive suppression and social sharing in their daily lives than healthy controls. Group differences remained when controlling for differences in mean experienced affect, except for increased suppression for MDD and increased sharing for BPD and comorbid MDD and BPD, which seemed related to these participants' overall higher levels of negative affect. Additionally, associations between within-person fluctuations in negative or positive affect and subsequent strategy use were equally strong for clinical and control participants, indicating that clinical groups did not differentially adjust the use of suppression and sharing to the emotional context. In conclusion, individuals with MDD and/or BPD showed increased use of suppression and sharing in daily life, which might contribute to, or follow from their emotional and interpersonal difficulties.