RecruitingBehavioural interventionParenting Skills Group for Mothers With Postpartum DepressionThe goal of this longitudinal study is to study the effects of a parenting skills group (Circle of Security Parenting, aka COSP) in mothers with postpartum depression. The main questions it aims to answer are: * Will changes in methylation of the OXTR rs53576 be apparent in mother and/or infant after having gone through the 8-week COSP program? * Will COSP participation be associated with improved symptoms of postpartum depression (over and above standard care), attachment style, and relational characteristics of the mother-infant dyad? * Will COSP participation be associated with changes in social behavior in the infant, and if so, do they persist throughout childhood? Participants will * Participate in an 8-week COSP program delivered remotely via Zoom. * Provide buccal swabs (mother and infant) to assess changes in methylation of OXTR rs53576 pre- versus post-intervention. * Complete a series of assessment questionnaires delivered remotely. * Videotape a play-based assessment in their home. * Receive infant developmental testing Researchers will compare characteristics of waitlist controls to those participating in the COSP program at the mid-way point of the program to see if the two groups differ.