It is recognized that parenthood in the context of psychosocial adversity can have negative implications for infant development. Parenting programs are the first line of intervention to improve outcomes for families; however, evidence for the effectiveness of group‐based, targeted early interventions is still scarce. Preliminary findings indicate Mellow Babies (MB) as a promising group‐based parenting program for families at risk for parenting difficulties. Using thematic analysis, we aimed to understand: (i) the aspects of the intervention that enabled parents to complete the program and (ii) the relational and behavioral changes perceived as valuable for parents and their babies post‐intervention. In total, 68 parents residing in the United Kingdom were interviewed after completing MB (49 mothers and 19 fathers; 88% self‐identified as British). Three themes and six subthemes were generated from the data. Parents identified several intervention components as beneficial, including the facilitators' interpersonal skills and multi‐dimensional, group‐based approach. Participant reflections highlighted three underlying mechanisms that enabled positive change: (i) the sense of community cultivated within the group, (ii) the process of formulating and re‐conceptualizing one's difficulties, and (iii) the opportunity to reshape interpersonal interactions. Findings are discussed within the context of perinatal and infant mental health.