Postpartum depression (PPD) is a depressive episode with onset after birth affecting up to 19% of women (O’Hara & Mccabe, 2013). Previous studies have found PPD to affect caregiving behaviors, such as infant directed speech (IDS) and speech turn taking (STT), due to depressed mothers speaking less frequently, being slower to respond to their infant’s behaviors, and using less affective features, when they speak (Saint-Georges et al., 2013). However, previous studies have also found sociodemographic factors to buffer the adverse effects of PPD on caregiving behaviors (Lovejoy, Graczyk, O’Hare, & Neuman, 2000). The present study examines the relationships between PPD, IDS and STT in a well-resourced Danish sample with mothers with and without PPD. First, we hypothesize PPD mothers to produce less IDS and STT compared to nonclinical mothers. Second, we hypothesize IDS to facilitate STT, that is we expect infants to be more likely to respond contingent after and IDS compared to a non-IDS vocalization. However, we expect PPD to moderate this  relation, in line with a previous study finding infants to be less sensitive to IDS after a Still-Face episode (Weisman et al., 2016), we expect infants of PPD mothers to be less sensitive to IDS compared to infants of nonclinical mothers. The present study comprises vocal data from interactions between 25 PPD and 53 nonclinical mothers and their 4-month-old infants. First, data was semi-automatically coded for mother and infant vocalizations. Presently, data is automatically analyzed using social signal processing in order to extract IDS and STT. Data is currently being analyzed. The study contributes to understanding the impact of PPD in early mother-infant interactions. Further, the study aims at informing clinical practice by specifying interactional difficulties in PPD, hereby offering ideas for which behaviors to target in interventions.