Purpose Defined as moderate to severe symptoms of major depression lasting greater than two weeks after delivery, postpartum depression (PPD) is a crippling mood disorder with extreme loss and incongruity in emotion. Despite the tools available for screening postpartum depression, there is a consensus that PPD continues to be underdiagnosed. Recent surveys assessing pediatricians and family physicians indicate that while practitioners believe that PPD is serious, they may not feel confident that they can recognize PPD, are unfamiliar with screening tools and under-estimate its incidence in their practice. This study was conducted to determine the knowledge and screening practices of PPD among certified nurse-midwives (CNMs). Methods A survey was distributed to 2100 CNMs attending the American College of Nurse-Midwives 50th Annual Meeting. Of these, 8.3% (n = 174) responded. The 121 respondents who provide care to postpartum women and/or infants less than one year of age were included. The 114 respondents who screen for PPD sometimes, often, or always were analyzed for their knowledge and beliefs. Results Of the 121 who provide care at least 10 hours per week and see postpartum women and/or infants less than one year of age, 94.2% (n = 114) currently screen sometimes, often, or always. 84.2% (n = 102) of CNMs screen often or always. Of the 114 respondents who currently screen, nearly all believe PPD is serious, common and treatable. Most believe that it would be feasible (91.2%) and that CNMs should routinely screen for PPD (93.0%). But half of CNMs (45.6%) believed health insurance would not cover treatment for PPD for many of their patients, and the majority of respondents (74.6%) believed their communities do not have adequate resources available to treat PPD. The majority of respondents had received formal training on postpartum depression in a variety of venues. However, only half (54.4%) of nurse-midwives reported the use of a specific screening tool or method, and nearly 60% estimated the incidence in their practice less than the published incidence (10-15%) in the general population. Over 30% are not confident that they would recognize PPD. In addition, less than two-thirds (65.8%) reported familiarity with available screening tools although 89.5% reported that they would use a brief self-administered screening tool to screen for PPD in their practice. Estimated incidence of own practice and general population were positively correlated (r = 0.738, p<0.01) and age is inversely correlated with PPD reported in clinical practice (r = -0.229, p = 0.016). The participants’ narrative responses indicated that they most frequently ask informal, general questions about depression and observe patient behavior to assess for PPD. They will then follow-up with a screening tool if warranted. Several cited literacy, language and cost barriers to the use of self-administered screening tools. Conclusions and Implications Nurse-midwives sampled believe PPD is serious and common, however their screening practices are irregular and they underestimate the incidence of PPD in their own practice. In addition, many are not aware of the available screening tools and are likely to miss dimensions of PPD when they screen by interview. Efforts to improve PPD recognition and treatment should involve nurse-midwives in screening promotion and thorough education in the use of screening tools.