Clinical practice guidelines and evidence-based reviews confirm the efficacy of tobacco dependence treatment for pregnant women. The purpose of this study was to examine tobacco dependence treatment practices among certified nurse-midwives who treat pregnant women who smoke. Midwives were surveyed to determine knowledge, perceptions, and beliefs about tobacco cessation treatment and to identify practice environmental factors that support treatment practices. Half of all midwives had not heard of the US Public Health Service Guidelines (5 A's) to assist smokers in cessation treatment. We found varying levels of adherence to the clinical practice guidelines. Nearly all midwives routinely ask, advise, and assess; while fewer encourage patients to set a quit date or discuss medication options (assist) and perform follow-up activities (arrange). Barriers significantly associated with clinical tobacco treatment practice are lack of training and competing priorities in the visit. One-office support, a system in place to provide smoking cessation information and resources, was associated with increased practice. In summary, midwives believe they should be providing tobacco dependence treatment, yet they identify a need for training. The findings of this study also indicate that sustained practice change, which includes the entire practice environment, should be targeted to enhance tobacco dependence treatment.