In many cultures, postpartum rituals are observed because they are believed to have beneficial mental health effects. Our systematic review examines the research literature investigating the effects of postpartum rituals on postpartum depression (PPD) to determine if the rituals protect against PPD. Methods: MEDLINE, CINAHL, PsycINFO, EMBASE, and the Cochrane Library were searched (from 1966 to October 31, 2008). Reference lists of relevant articles and links to related articles were also examined. Both qualitative and quantitative studies that focused on traditional practices and rituals in the postpartum period (that is, within the first year following childbirth) and their relation to PPD or mood were included. Results: Seventy-two studies were considered, with 12 meeting the inclusion criteria. The data were summarized according to the type of ritual including: organized support, diet, and other or multiple postpartum practices, and evidence for or against a protective effect on PPD. Although limited, not all studies suggested that the rituals prevent PPD. Overall, there is some evidence that postpartum rituals dictating appropriate and wanted social support may be of some protective value, depending on numerous contextual factors. Conclusions: This area needs more culturally sensitive and systematic research. Current studies suggest that the key protective element may be the presence of welcome support rather than the specific ritual.